The two stylus works the same. Both pressure sensitivity and the button works on both the Max2 and the Note8 with both stylus.
The note8 stylus seems to be a bit more sensitive, needs a bit less pressure, but this maybe because I use the soft (black) tip, which is capable of bending a bit (the note8 pen has replacable tip, and I got softer and harder tips to choose from). Also this soft head feels a bit differently (more sticky to say), but technically works the same.
Maybe when Onyx will supply replacement tips for the pen, it will be exactly the same.
The original stylus that I got with the device has no button,I’ve purchased a replacement one for half price when Onyx offered that promotion for Max2 owners. But that original stylus also works on both the Note8 (and even on my old Note4).