For years, Joe Belfiore and David Treadwell waged their own separate battles at Microsoft Corp., with Belfiore helping to lead the upstart Windows Phone division and Treadwell heading Xbox software and services engineering.
But last month at Build, Microsoft's annual developers conference, they shared the spotlight - a sign that their teams, and the company as a whole, are increasingly marching to the "One Microsoft" tune.
"One Microsoft," a deep reworking of Microsoft's organization, is designed to eliminate the distractions and infighting that some say stifled innovation and caused the software giant to fall woefully behind its competitors in critical areas.
Belfiore and Treadwell are among the top executives in the Operating Systems Group, formed during a companywide reorganization last year. It brings together some of Redmond, Wash.-based Microsoft's most famous brands - including Windows, Xbox and Windows Phone - which had previously been siloed in different divisions.
In their roles, the two veteran employees are central to the "One Microsoft" effort, bringing together everything from product design to schedules that range across Microsoft's operating systems. They also work closely with other groups within the company.
Belfiore and Treadwell are, respectively, in charge of the front end and back end of operating systems, including the Windows PC, tablet and phone platforms.
Belfiore leads the team responsible for the "user experience" for Windows PCs, tablets and phones.
Treadwell heads the program management team that plans and decides what goes into the core operating system for PCs, tablets and phones, as well as for Xbox, Windows Embedded (which runs industry devices), and Perceptive Pixel large touch-screen displays.
During Build, Belfiore took the stage first and, in his usual conversational, upbeat manner, introduced Cortana, Microsoft's voice assistant for Windows Phone.
Later that morning, Treadwell, in his friendly, enthusiastic way, announced "universal Windows apps," which makes it easier for developers to write once and have their apps run across Windows PCs, tablets and phones.
Cortana and universal Windows apps are two of the most visible examples of Microsoft's effort to foster a more collaborative company culture - an effort that began with the companywide reorganization put into place last July by previous CEO Steve Ballmer and being continued by new CEO Satya Nadella.
Cortana, for instance, relies heavily on Microsoft's Bing search engine, meaning the Windows Phone and Bing teams had to work closely together.
Treadwell's announcement, meanwhile, came as Microsoft launched Windows Phone 8.1 six months after Windows 8.1 was introduced to the market.
That marked the last time significant updates were planned for and released on different schedules.
"We had to finish Windows 8.1 Update, Windows Phone 8.1, Xbox One," Treadwell said. "Now that those are done, we are now on the same logistical schedules. We're going to have one common OS schedule and everything's going to be aligned with that. We're doing common planning now, common priority, common release schedules."
Belfiore, 46, the more extroverted of the two, is a familiar presence at Microsoft conferences, frequently giving demos on stage.
He is "colorful, excitable, authentic and genuine ... very passionate about the end user experience," said Terry Myerson, head of the Operating Systems Group.
Belfiore became enamored of computers early on - ever since he found out that a kid in his neighborhood in Clearwater, Fla., had a dad who owned a Timex Sinclair 1000.
"I'd go over to his house to 'play with the kid' and I just wanted to play with the computer," Belfiore recalls. "I used to write these BASIC programs where you'd sit down and have a conversational interaction" using text on the screen.
After graduating from Stanford with a computer-science degree, he arrived at Microsoft in 1990, intrigued that the software giant was "building state-of-the-art experiences in Word and Excel."
He also had been turned down earlier for a job at Walt Disney Imagineering, which designs and develops the Disney theme parks. He saw Imagineering as a place that exemplified using technology to create emotional experiences for people.
Microsoft, he came to feel, could do the same with its technologies - something he's focused on at the company, including as general manager of the Windows XP user interface, and as a previous leader of Zune software and services, Media Center and Windows Phone program management and design.
Belfiore's role now is to think about creating the best customer experience, leading him to advocate, for example, that Treadwell's team work on creating a core operating system that will enable hardware manufacturers to build devices in a range of prices.
"How can you engineer a great experience? That's really been the focus of my career," Belfiore said.
Treadwell, 47, is thoughtful, patient, detail-oriented.
He focuses on infrastructure, Myerson said, making sure that things are "very well built, well architected, well designed."
Treadwell, who grew up in Baltimore, also became fascinated by computers early on. He recalls being enthralled by "the things you could do" with his grandfather's TRS-80, on which he wrote BASIC programs to play blackjack.
He came to Microsoft in 1989 after receiving his electrical-engineering degree from Princeton, drawn by the chance to work on the then-nascent Windows NT under David Cutler, considered the father of that operating system.
Then and throughout his career at Microsoft - which included leading the .NET developer platform, Windows Live Platform Services, and Xbox software and services engineering - his motivation has always been to build great products that have a positive impact.
Treadwell's role today is to see how Belfiore's and others' needs fit into the big picture, playing the mediator and balancing the needs of Xbox with those of Windows and Windows Phone, for instance.
Within the Operating Systems Group, cooperation is a requirement for Belfiore and Treadwell in their jobs, but there are built-in healthy tensions.
Myerson likens their roles to that of painters, and plumbers or electricians - both of whom are essential to the building of a house.
"Joe is just a magnificent painter. Dave is much more a plumber or electrician," Myerson said. "Together we all come together and build this fabulous house that is Windows."
Throughout their time at Microsoft, Belfiore and Treadwell say, they've taken part in collaborative efforts across divisional lines.
The Windows Phone and Bing teams had worked together on previous versions of the smartphone before deciding in 2012 to collaborate on Cortana.
Teams from the two divisions met regularly, on campus and at a bar in Bellevue.
One particular sticking point: finalizing the name.
Some people said Microsoft had spent a lot of money and effort building up brands such as Bing, and it made sense to capitalize on that with a name like Bing Assistant.
Others, including Belfiore, thought users would find it more intriguing and be able to more easily make an emotional connection if it were named after Cortana, an artificial-intelligence character who helps the protagonist in Microsoft's "Halo" video games.
Belfiore sees the reorganization last year as the formalization of a shift toward more collaboration that has been going on for a while now.
He and Treadwell acknowledge that such collaboration has become easier. Before last summer's reorganization, for example, each division had its own design team. Now, they've all merged into one.
And this year, almost all of Microsoft's engineering teams - from Azure to Office, Bing to Skype - took part in the crafting of a priority memo prepared by Treadwell's team that states what the company will be including in its next big release of Windows.
"Before, there was a Windows team, a Windows Phone team, an Xbox team. While there was general agreement of the value of (having a) common core and consistency of design, there were organizational lines that we had to cross to achieve that," Treadwell said. "There just aren't these barriers now."
Explore further: Microsoft VP: iPhone, Android offered mobile cues