Both SAT and ACT have reading sections -- and they don't get much press. They are pretty typical read-the-passage-answer-the-questions multiple choice style sections. But, there are some subtle but important differences between the sections.
First, and most importantly, there is a timing difference.
SAT: 65 minutes, 52 questions, five passages (one is actually a pair of passages) with about 10 questions for each passage/pair of passages.
ACT: 35 minutes, 40 questions, four passages with 10 questions each.