His departure from Apple was more to do with personal disagreements with the board of directors rather than any creative differences, so I've been led to believe. Apple was performing fairly badly at the time they fired him, and Job's certainly didn't make a fortune out of NeXT, (they lost a lot of money on the hardware) in fact I'd say it was only Apple's purchase of NeXT that made it a success. Of course this paid off in the long run, and led to the creation of OS X.
Here is the disagreement:
Steve wanted to invest money into Mac OS to integrate Unix foundation.
Board don't see why people would need make Mac OS unix.
NeXT was under contract to not to compete with Apple, so NeXT can only sell to very small number of customers. In addition, NeXT was ahead of its time technically. Result, OS X is delivered 10 years later after Steve was back at Apple.
As I said, Steve owning pixar resulted in the modern apple. I wrote an article on Pixar on my site.