I personally see no difference in either AC/DC or BLS rythyms... As a beginner (as in just picking up a guitar) everything is hard at first. It's whatever you adapt to first really. I started on Metallica and a lot of Jimi Hendrix (among other blues players), and Dave Matthews (Chords galore). AC/DC always came easy to me... When I finally did get into BLS I found myself not even wanting to learn it... I mostly just listened to Zakk play. The BLS I have learned is all from ear and is all from just messing around with stuff that Zakk is known to do. His stuff is pretty basic... His songs are pretty known to have slow dragging rythyms and fast leads... Power chords, a few single note riffs, and a whole lot of pinch harmonics... Megadeth takes more of a Metallica approach to all there stuff... mixing it up between chords and single note riffing... As far as which is more difficult for beginners... AC/DC or Zakk... i would say for a beginner... if you want to learn some easy rythym check out some Zakk Wyldes BLS... if you want to check out some solos that are on the easier end of the spectrum (still very respectable in all respect) check out Angus' work with AC/DC... There rythyms are spotty. Some are easy to pick up and some aren't quite as easy... hit or miss really...