Bite point adjusts the point in the piston/lever stroke where the pads contact the disc
Reach adjusts the starting point (away from the bars) of the lever
If you look at what they are actually doing when you twiddle the knobs you will see one moving the piston in and out (bite) and one moving the lever blade. If you adjust one it will affect the other so you have to balance/do them together.
Best way is to set the reach first to work out where you need the lever in relation to your fingers. Then if you need to adjust the bite point to change that, and then rest the reach back to the right point after. Some people do it the other way, set the bite point first, then reach, both methods work!
I’m sure there’s a video on YouTube explaining it (there is for most things) visually if you can’t wrap your head round it from the description
