Zelda is a Wii U game, ARMS to me looks like it's using tech specific to the Tegra processor such as better shaders/lighting effects. 

Looks to me too like the characters in ARMS have a higher poly count than anything on the Wii U (yes, Zelda included). Of course Zelda has a larger scope given the nature of the game. 

Zelda is the most beautiful but Arms looks better from a tech perspective. It makes sense though since is not an open world game. 

Best looking so far imo on a graphical sense is Odyssey, BOTW in an artistic sense is the best looking game do far.

This is great.

I think ARMS always was 1080p, Mario Odyssey is totally different story, it was revealed almost whole year before launch, so definitely don't need to look too much at that reveal resolution for Mario Odyssey, I epecting that Mario Odyssey will be at least 900p/60fps at launch.

Models look much more advanced poly-wise and shader-wise than they seemed to me in January. Still, fighting games often have higher poly models than other games.

ARMS is the next Splatoon, Nintendo keeps adding terrific new franchises to their roster.

Hella well optimized. Good stuff

Gotta agree with soundwave, ARMS looks so much more vibrant and clean, BotW looks rough around the edges and some textures are pretty atrocious. ARMS is a much smaller scale game so it makes for it to be extremely polished compare to the giant open world of BotW.

I would be very surprised if they weren't using the same engine.