They are both very similar scores, but which one should I submit to colleges?
According to this concordance table, http://www.studypoint.com/ed/sat-to-act-conversion/ , the 33 is better because 1450 equates to the low end of a 32. Submit your 33 ACT no questions asked!
I would sent both
Send the 1450 only, don’t send the 33.
33 is better. Just send that, it’s excellent!!
If it is a pure digital choice, 33 is better. If this was your first sitting or if the scores you shared were not already “super scored” by you after multiple sittings, consider taking 1 or both one more time if you are shooting for a tip top school. The one slight advantage of the SAT, if you only have the stomach for one, is that many schools super score the SAT but only formally consider the highest composite ACT, although some schools will require a submission of all scores of either the ACT or SAT (see Yale) or both (Stanford) if both were taken.