Re, Def Leppard:
Pyro was the beginning of their more "poppy" sound. Still a great record but I prefer the more metal sound of High n Dry.
TSO:
Yes, they are much more classically inclined; also more bombastic and theatrical sounding.
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"The cat is the most ruthless, most terrifying of animals." - Spock in the "Catspaw" episode of ToS Season 2.