How many quarks must I distinguish?
They come in 6 flavors. But each has an antiquark so that would be 12.
Electron and positron are also particle and anti-particle and are considered as different particles.
There only difference, as far as I am aware of, is the opposite electric charge.
How about "color charge" of quarks. There are 6 types: 3 "colors", 3 "anti-colors".
Does this mean there are 36 or even 72 different quarks?
There are 3 generations, in each generation there's a doublet of two quarks, makes together 6 flavors. For each of those 6 there are 3 colors, makes 18. If you count antiparticles separately, we are at 36. You could further count right- and left-handed particles separately, that would make 72.
At the end of the day, there's no completely consistently defined notion of "counting types of particles". It depends on the context.
