I’ve long wondered about the subject and how to use the different commands. My fingers almost always just type apt-get.
Recently I noticed a slight difference when using apt on Ubuntu version 14.04 LTS and UM 16.04 LTS; the command apt autoremove works in UM 16 but not in Ubuntu 14 [apt-get autoremove works].
I decided enough was enough and did some searching … bottom line for me is I will switch to apt vs apt-get and ignore aptitude.
I decided this after reading, from what I term the horse’s mouth…Debian Administrator’s Handbook