Your differences could create a lot of frustration between you, making it hard to get along as equals. You'll see your friend as unpredictable, immature and unruly, and it will become all too easy for you to slip into a controlling role, as if it's up to you to keep them in line. The fact is, they have goals, drives and ambitions that are out of your control, and you'll have to accept that.
If you can't, your relationship dynamic will devolve into a series of power struggles to determine who's top dog. But really, there shouldn't be a top dog at all; friendships are supposed to be between equals. You'll have to call on your own maturity and self-control to create a better dynamic between you, first by controlling your own behavior and attitude rather than trying to control your buddy. Once you do that, you may be able to reach the more positive potential of this aspect -- that of creating a strong, driven working team with different yet complementary strengths.