what makes AC/DC rock
that is simple, the rhythm section, the rhythm guitarist, bass player and drummer set up the groove, rock solid 3 piece groove. no frills, no fancy chords, just good solid vibe. then you take a person who wants to destroy their voice in one song to sing, and a hyperactive guitarist who studied classical music and turn them loose. That is it in a nutsheel.
I am sure long nights drinking in stripclubs has helped
but all in all, it is the full frontal attack of the most basic formats ever put together
Just look this, those guys are very great at what they do, they do not do much, but they have practiced that little bit till they can do it in their sleep. and they do not stray far from a very success full formula: great intro with a hook that gets you stomping your foot through the floor, A chorus that has you shouting at the top of your lungs and a guitar solo that has the entire arena playing air guitar.
Now that is rock and roll.
Def Leppard's approach is different,it is over producing a song. Worked well for them. If you tear down a DL song it is not hard, it is just the fact that every note is placed right where it needs to be. I bet the productioncost in studio between both those bands is night and day, and they both rock.