Manny Medina is a guy in the know. He's one of a growing number of Seattle-based techies who has jumped between the two. And while both companies share a reputation as industry pioneers, he said the experience showed him some stark differences that set them apart.
"If you want to get a job at either Amazon or Microsoft, of course you need to be technically-minded and be able to see how your work applies across the business. But both companies take quite different approaches to that," Medina told CNBC Make It.
Amazon, where Medina started out his career in the Web Services team in 2003, takes a bottom-up approach to business, looking at the minutiae and small, incremental wins, he said. Microsoft, meanwhile, works from the top down and focuses on the overall end goal.
"Amazon stresses over pixels and Microsoft obsesses over strategy," noted Medina, who left Amazon for Microsoft's business development team in 2005.
Those distinct approaches have to do with their business models, he said. As a retailer, Amazon's margins are smaller and so each individual decision needs to demonstrate overall value. On the other hand, Microsoft's tech business is higher-margin, meaning it can take a more overarching view.
But it also comes down to their differing leadership, he continued.
As CEO, Jeff Bezos remains very much "embedded" in the everyday aspects of Amazon. That means potentially running into him — a lot — and also being prepared to answer to him.
"At Amazon, if you come to a meeting, especially with Bezos, he's looking for an opinion and facts: If you don't have one, no decision is a decision to stick with the status quo. Not having enough time is not enough," said Medina. "In some ways it's beautiful because of the drive it gives you, but it can be very high-pressure."
Meanwhile, Microsoft has seen several CEOs since it was launched by Bill Gates in 1975, and has evolved under different leaders, most recently, CEO Satya Nadella. As a result, it emphasizes "good communication and (staff) don't have to touch on all areas of the business," said Medina.
So, which of the two would he recommend?
Well, neither, actually. After eight years working his pick of "juicy, sexy jobs" at Amazon and Microsoft, in 2011 Medina decided to jump ship and launch his own start-up – something, in hindsight, he said he wishes he'd done sooner.
"My life is not a very good example of a good life lived," he said. "If I were to do it again today, I would work at a start-up straightaway."
"The amount of experience you get at a start-up is far greater and the basket of problems you can work on on any given day is so large and so insightful it can satisfy any curiosity."
However, his experience learning from two of the best has certainly come in handy. After his first business failed, Medina and his three fellow co-founders created Outreach, a communications platform for salespeople, which is today valued at $500 million.
Medina said he runs it like a hybrid of the two tech behemoths.
"Economically we look like a Microsoft," said Medina, referring to company's high-margin, service-based business model.
"But we also take learnings from Amazon," he continued, noting that, despite its huge growth, Amazon has maintained a "Day one" mentality, which provides a good model for start-ups.
"Even though it feels like we're winning, we're growing, you can't take your eye off the ball: The market is very vast," said Medina.
"So as CEO I try to understand the minute detail. I use Amazon tactics to drive Microsoft growth."
CNBC Make It reached out to Amazon and Microsoft for comment, but they were not available to respond at the time of publishing.
Like this story? Subscribe to CNBC Make It on YouTube!