Besides whether or not cursed modifiers are allowed, are there any other differences besides true and glitchless?

Nowadays almost none. However, back in the day there used to be glitches that would not be allowed. An example of this is the chaos distortion glitch shown here: And the wrong warp glitch shown here: Both have been patched and to my knowledge no glitches remain within the game that effect speedrunning. So i would say that there is currently no difference between true and glitchless besides cursed modifiers.