They're not even really the same thing. Clarke was somewhat incapable of writing true tension, at least most of the time. His prose is a cut above that era of scifi, I think, and his ideas are great, and sometimes sad stuff happens in his books, but the overall impression is never one of suspense. The whole series is great, though. He didn't make the mistake of dragging it out too long that others did. I'm curious to see how Clarke's version compares to Kubrick's.
I have to disagree with you there, the first part of the book is rather tense, you as the reader understand the danger that the sabretooth(?) poses and it creates moments which draws you in to hoping and praying that the protagonist primate survives as he goes through mental and social evolutionary changes; compared to the movie it shows development of complex (for them) concepts where the movie really can't explain this other than "oh I have a bone, I can hit stuff now".