The sample articulation differences are substantial: the default snare in the EZdrummer 2 core library includes 50 hits across 17 velocity layers with three articulations (Center, Rimshot, Sidestick). In SD3, the same articulation features , with a total of eight different snare articulations , including flams and ruffs. The Superior Drummer 3 core library also supports positional sensing for more nuanced playability, while EZdrummer 3 does not.
Toontrack makes both.
SD3 transforms its massive sample pool into an "incomparable palette" through several integrated tools: Superior Drummer 3: The Making of the Core Sound Library superior drummer 3 core library