Tidal Wave/Shockwave is a huge difference. I like the US/EU version I have well enough...up until I see pics of the Japanese release and am reminded how poor mine looks.
But they're so different they're almost like different characters.
Not Armada but the other very significant difference I'm aware of is Energon Scorponok. Neither really nails the G1 colours, but they are both quite different from each other.
assembling a Neo-G1/TF:TM cast. Please PM if you have (or know of) the following at a reasonable price: Classics or Henkei Prowl, Astrotrain, Ramjet, Skywarp, Sunstreaker, Sideswipe, Blurr, Perceptor, GDO Wheelie and Springer, or 3rd Party Motobot Arcee, FP Springer, iGear Ratchet and Ironhide, City Commander (and/or Ultra Magnus), Starscream (deluxe) Coronation add-on, or Spike and Daniel in their Exo-Suits.