Today is the first day that someone other than Jeff Bezos will be CEO of Amazon. As Andy Jassy, the longtime Amazon employee who has served as CEO of AWS--the company's cloud computing platform--takes over from the company's iconic founder, it's natural to compare the two men.

Most reports suggest that Jassy is just as competitive as Bezos. He's also known to focus on small details and ask intense questions of his team during presentations--just like Bezos. There is, however, an important difference between the two, and it has everything to do with the way they view Amazon. 

First, though, I don't think there's any question that Andy Jassy is about as much an insider as you can get at Amazon. He's one of the company's earliest employees, and working at Amazon has defined his entire career. Until today, he started and led the company's most important and most profitable business unit. He's not an outsider.

Except, he's also not Jeff Bezos. That, it turns out, is important for a few reasons.

One of those reasons is that, at least according to reports from people who work for him, Jassy has a far better understanding of how work fits into people's lives. More specifically, Jassy understands that, for most people, work and not work are two different things. 

It hasn't always been clear that Bezos understands the distinction. Bezos even described his distaste for the idea of work-life balance in his book, Invent and Wander:

I get the question about work-life balance all the time. I don't even like the phrase "work-life balance." I think it's misleading. I like the phrase "work-life harmony." I know if I am energized at work, happy at work, feeling like I'm adding value, part of a team, whatever energizes you, that makes me better at home. It makes me a better husband, a better father. Likewise, if I'm happy at home, it makes me a better employee, a better boss.

I feel like it's fair to point out that Bezos's track record as a "better husband" might leave something to be desired. I don't say that as a personal attack, but merely to suggest that his thesis is flawed.

Jassy, on the other hand, once told employees, "We're not put on earth to work," at least, not entirely. The point was that he seems to have something that his former boss may have lacked: perspective.

That's going to be important as he takes over one of the largest and most important companies on earth. It'll especially be important as that company faces intense scrutiny over everything from how it treats workers at its distribution centers, to the way it interacts with the third-party merchants who make up the majority of sales on its platform, to antitrust concerns from regulators and lawmakers.

Having a little perspective is always useful, but it can be a challenge, especially for founders. When you think about it, that actually makes sense. Founders like Bezos tend to internalize the thing they are building. It's easy to let it consume everything about your life. It's easy to treat your work as the main thing, to the detriment of everything else.

I call it the "true believer" problem. It's where a founder only sees the thing she built as she imagines it in her mind, not as it actually exists. There's often a huge disconnect between the two, and identifying it requires perspective. For example, you only see your good intentions, even if the world around you sees things very differently.

Jassy, however, will have to figure out how to balance not just his personal life and his work, but also the demands of customers, employees, shareholders, and lawmakers--each of whom has different perspectives. Bezos seemed to hyperfocus on specific areas of the business, sometimes without seeing how it might affect the bigger picture. That, if nothing else, might be Jassy's biggest challenge and--if he pulls it off--the key to his success.