There is very little difference between the master password and secondary password (lololol I'd be the expert eh?)
The only one is that you cannot see or change the master password with a secondary password. Someone who logs in with a secondary one can see all other secondary passwords, remove them, add more, and of course all the other base functions.
Technically the entire base could be ran and upgraded by a secondary password with someone uninvolved, other than using the builder, able to mess around like this because they have the master password.