I know that if you want to say "The man who is reading the book" you say:

Hon o yonde iru hito wa....


Can you also say:

Hon o yomu hito wa...


Thanks.

Yes, you can. But that would equal something to the effect of " The man/men who read book(s) [as opposed to something else]"

It depends on what you mean by "can you also say". "Hon o yomu hito" is a valid Japanese phrase but it doesn't mean the same thing as "Hon o yonde iru hito". "Hon o yomu hito" would generally mean "The person/people who [habitually] read books" or sometimes "who will read a book".

Thanks, I think I understand the difference now.