Neither one, really - they're both unique in that way.
In AC/DC, each song is a "mode" with its own song jackpot goals...and when you hit 8 of the "song related shots" you can hit the jukebox and choose a new song "mode" (or not & stick with your current song).
In Avengers, it's kind of like Monster Bash - each shot represents a character...shoot it enough time and it starts their "mode"...but it's more like a "scoring feature" - and it stays active till you complete it - it's not timed. Then once you do that - hit that character shot a bunch more times to start a Vs. mode - which always start as 2-Ball multiballs.
Neither game has a traditional "hit scoop, start timed mode, complete, get set up for next mode" thing.