Specifically, what goes on when you get prompted by the GUI to enter your password in order to make a transaction?

Does the code run the default walletpassphrase <your password> <timeout (seconds)> command line with the default 60 seconds or something else happens?

I use the walletpassphrase to see if I still can remember my password and I don't want to transact, so im curious about what goes on when the GUI unlocks it when making a transaction.