Before reading this article on the differences, I’d been stuffing all my export, alias and other things in either .bash_profile or .profile files on my Macs.
Though most settings will run just fine in either file, there is an important difference between .bash_profile and .profile:
If you need something to be executed or sourced (i.e. source ~/.profile) as you open a new terminal tab or terminal window, stick it inside of .bash_profile. Items in .profile only get run once when you login.