Perhaps interchangeable but slightly different. Different prepositions. I believe "Point" is just a coincidental example that is interchangeable with "at" & "to". In this case, maybe "at" = "in the general direction of something " I think the difference usually has to do with transitive vs. intransitive verbs. That is, active or passive action. 1) I arrived "at" his house. (Technically you didn't do anything - something just happened, you "arrived"). 2) I drove "to" the store. (You actively DID something, an action occurred). I hope that helps.