Def Leppard has personnel issues that shaped a lot of their music, coupled with their producer, John "Mutt" Lange who managed to morph their sound into sounding like other bands he produced in the past -AC/DC, Foreigner, et al.
Moving on with a one armed drummer, gave their sound a more electronic sound coupled with the other technological aspects (sampling, et al) made their sound a lot different -but often imitated (i.e. Bon Jovi)- from other arena bands.
Their first 2 albums featured the 2 pronged guitar attack of Steve Clark & Pete Willis. Clark's playing more raw & sloppy, Willis's approach more polished & clean. Trouble was that Willis had a bit of an alcohol problem and was fired during the recording of
Pyromania and replaced by Phil Collen. On
Adrenalize due to the death of Steve Clark, Phil Collen recorded both his own guitar parts and Clark's... In interviews he indicated it was so stressful for him that it nearly led him to quit the band. His style was/is closer to Willis's polished & clean so trying to play more raw like Clark was not at all easy for him. I'm guessing he was pretty thankful when Vivian Campbell was hired.
I've thoroughly enjoyed most of Def Lep's albums (except for
X which was unmitigated crap from start to finish). They're actually 2 extra generations removed from rockabilly:
Rockabilly begat British Invasion, British Invasion begat Glam Rock, Glam Rock begat Def Leppard
Whereas Guns & Roses would look more like this:
Rockabilly begat British Invasion, British Invasion begat the Stones, The Stones begat Guns 'n' Roses (and countless others)
With bands like Skid Row, Motley Crue, Great White, and Poison I hear a more direct:
Rockabilly begat hair metal
With bands like Metallica I hear more of a:
Rockabilly begat British Invasion, British Invasion begat Heavy Metal
Heavy Metal begat Deep Purple, Led Zeppelin, Rainbow, & Black Sabbath
and those bands begat Metallica