How many types of peppers are there, what's the hottest one, and doe the colors taste different??
Theres alot of different variety of peppers out there, from bell peppers to the spicy jalapeno. The colors do have a different flavor profile, this is most noticable with green bell peppers (sorta bitter) and red bell peppers (sorta sweet) tasting, side by side.
The hottest pepper that is widely available is a ghost pepper or ghost chile. There is a hotter variety though and that one is called a scorpion pepper (this one is harder to find at your local grocery stores though).
Heat is measured in Scoville units. A pepper with around 4,000-6,000 Scoville units will be mildly hot but not overpowering. Habanero/Scotch Bonnet peppers can be in the 40,000 to 60,000. These have a fiery "heat" but once you get past that there is a lovely almost floral note to the flavor.
The hottest pepper is the Carolina reaper