Four EL34 power amp tubes. The clean channel is worth the extra $300.
The DSL has the classic Gain and Ultra Gain channels (no clean) Four ECC83 preamp tubes
Four EL34 power amp tubes.
The combo should sound the same if it has the same tubes/preamp circuits. The 2x12 cabinets can sound different than the 4x12's. It all depends on the type of speakers, and if the cabinet has a closed, or open back.
"Somebody put something in my drink, Yeow Yeow!"