Looking at your picture you have two different types of taps. The upper (farther from the camera) are called spiral flute taps, the chips are driven out the back of a blind hole. the other three are spiral point taps, the chips are driven out the other end of a through hole. (if you already know this, forgive me)
Classes have to do with accuracy of the grind. Some taps (don't remember the way the numbers go) cut closer to the standard size, (are more accurate) For general use the less expensive taps (the ones we use every day) don't need that degree of accuracy. I can't explain the classes on your taps.
All five of them are coated with a 'slick' 'hard' coating, improving their cutting ability and life. There are brand names for these coatings, (there are many), all are better than none.