apt is a newer, more user-friendly front-end for apt-get and apt-cache.
apt = combines commands like install, remove, update, upgrade into one tool, with prettier output
#apt-get = older, lower-level, more script-friendly
For normal use, just use apt now.
For scripting where 100% backward compatibility matters, use apt-get.
I don't know if they modified apt at all. I know they have their mint tools that call apt through some python code, like mintinstall = apt install <package> for the software manager and mintupgrade = apt upgrade for updating mint versions ... Etc