Steve Jobs and Bill Gates are both well-known, but many see Jobs as an icon and some attribute it to his almost rags to riches tale. While both went to college, Jobs was adopted and purportedly had a rough upbringing. Jobs also dropped out of college, and the way the story is told is that he took a few classes that helped him develop the type faces on the Mac. In any event, his rise to fame was a little rockier than that of Gates.
Gates, on the other hand, benefitted from Harvard education (until he dropped out too) and developed the Microsoft brand, making sure he reviewed every line of code before it went out. That was in the early days when he had time. Gates, since his early days of overseeing his company become a multinational conglomerate, has also been involved in a number of philanthropic ventures, and he is equally known world-wide.
They seem to be both known worldwide, but for very different reasons. While Jobs is seen as an icon, Gates is viewed more as a philanthropist. Not that one is more famous than the other, but it is more what they are known for.