According to some Japanese dictionaries, they do have differences in use, but in most cases, they are quite interchangeable. Maybe they are similar to the English expressions "to do ___", and "in order to ___." For example; I came here to see you. I came here in order to see you. ← maybe this has more emphasis on "to see you" than the other. あなたに会うため、ここに来ました。 あなたに会うために、ここに来ました。