Which is harder, the ACT or SAT?

Which is harder, the ACT or SAT?
My son has to test for a program (currently in 7th grade), and he has the option of the SAT or ACT. He is not much of a writer so leaning towards the ACT due to the essay section in the SAT. Which test has the more difficult question in regards to the math and science sections? Which would seem to be, how do you say, ‘user-friendly’ for a 13 yr old??

Actually both are pretty difficult. The ACT also has a writing section which must be completed in 30 minutes (argumentative essay) and most colleges require the written portion score if not all. He should practice exams for both and see which one he does better in. Also, the SAT actually takes away points for wrong answers unlike the ACT. I’d say ACT for him. That’s what most people take.

Act grammer/english part has 75 questions which must be finished in 45 minutes
math part- 60 questions, 60 minutes
reading part 40 questions, 35 minutes with about five really long short stories or excerpts
science part is same as reading.

This test isn’t to see how smart one is, but how well they can take a test and find info. Especially the last two parts, though knowing science and math may help.