Oh yes, of course. But you can also compare that with OpenGL vs. Vulcan or DX9 vs. DX12. API obviously matters.
I am not too worried about OpenGL because newer software and games tend to use Metal directly anyway (or something that leverages Metal) and older OpenGL stuff is probably less demanding. And then, OpenGL can be relatively efficient (as far as you can call OpenGL efficient) emulated on top of Metal anyway. It would be curious to run GFXbenchmark on M1 with both OpenGL and Metal, that would give us a measure of how efficient Apple's OpenGL wrapper is.