I don't remmeber the arcade being a whole lot faster, though it was noticable. The power ups on the other hand seemed to rush off screen and weren't nearly as accomadating as they are in the PCE verison. That and the whole game was streamed together I believe. That said though it was about the same difficulty depending, of course, on how many quarters you had. Dragon Spirit, TMNT 2, Ninja Gaiden, Double Dragon had probably consumed a small fortune in quarters from me before the arcade near my house went under. Its a shame really even though thats probably what allowed me to save up for a SNES.
On the Famicom verison I remember it being different and that it was much easier (as I had actually beat it once or twice). Thats about it as I never really got into playing it a whole lot and its been ages since I've touched it. The famicom was all about Captain Skyhawk and strangely enough Sky Shark for me. Sky Shark though was brutal and every bit as mean (i.e. cheap) as the PCE Dragon Spirit.