They’re just different pilots ryming speak that represents the various emergency transponder codes of 7500, 7600, 7700.
75 …we’re Still alive…illegal interference with the operation of the aircraft but I can’t use the radio to tell you, ie an intruder in the cockpit, hijack.
76…box of tricks, as in the electricals such as radios, navigation equipment etc has failed.
77 …we’re going to heaven, an event is occuring that puts the aircraft and it’s occupants in grave danger.
Guess sometimes the UK and USA are separated by a common language and common things appear slightly different depending on which side of the pond our experience has been.