The ACT includes 4 sections – English, Math, Reading and Science. The SAT also includes 4 sections – Reading, Writing and Language, Math without a Calculator and Math with a Calculator. Both tests also include an optional essay. From this section breakdown, it is evident that the content for both tests is largely similar except for the inclusion of a science section in the ACT. So, if you’re a science-inclined person, then the ACT might appeal to your more with their science-specific section. Of course, the SAT also includes some science related passages, however, the emphasis is a lot lower.
Moreover, the SAT has a no-calculator section, so if you are entirely not comfortable with the idea of doing math without a calculator, you may gravitate towards the ACT. The English sections are largely similar for both, however, the SAT does place a greater emphasis on testing challenging vocabulary.
When it comes to the essay section, the requirements vary between the tests. The ACT essay asks for your personal opinion and you are expected to think of examples to support your claims. On the other hand, the SAT essay requires you to read a passage and analyze the author’s argument through the use of evidence, reasoning, or stylistic and persuasive devices.