So far there are five different types of Lesson cards. They are as follows: Potions, Charms, Care of Magical Creatures, Quidditch and Transfiguration. Each lesson is represented by their own symbol and color.
Potions is green and it's symbol is a cauldron. Potions is really good for a never ending deck. You can split your cards between healing and non-healing cards. Healing cards let you put cards back into your deck that are not healing.
Charms cards are blue and it's symbol is a heart. They are fast damaging cards. It's usually best to combine these cards with Potion cards.
Care of Magical Creatures are brown and it's symbol is a paw print. All creature cards are in this lesson. It is the most commonly used lesson as well. Creature cards are most effective due to the fact that they deal damage as long as they are in play.
Quidditch is yellow and it's symbol is a golden snitch. These cards are based on the game and deal as much damage as any bludger would. That of course depends on the card.
Transfiguration is pink and it's symbol is a butterfly. This is mostly a defensive type of lesson. It gets rid of other players cards. It's the best type to play against and/or with Care of Magical Creatures lessons.