Asimov was actually a scientist (bio-chemist, I believe) of some renown as well. He made science simple and his non-fiction books on biology, chemistry and physics were aimed at the layman. In comparison, Clarke was a nobody.
To be honest, I never really read his science fiction books. I know him through his science books. I did read a couple of his Perihelion series that was based off the Robots universe, and some of his other short stories, mainly humourous ones.