There are 3 types of chests: Small, Large, and Ender Chests. There are 6 types of Small Chests, 3 types of Large Chests, and 1 type of Ender Chest as well as the special event chests!
Small Chests are obtained through mining a particular amount of blocks in the biome you have unlocked most recently. There are wood, iron, silver, gold, diamond, and mythical small chests. Small Chests can yield Blocks, Companions, Artifacts, Abilities, Runic, and rarely you could get a pickaxe.
Large Chests cost 150 runic for gold, 500 runic for diamond, and 800 runic for mythical, and yield significantly more blocks than small chests. It yields 5 different variants of blocks (each different variant has 21-71 for rare blocks and 74-282 common blocks) and an increased chance for a pickaxe, companion, or chest treasure.
Ender Chests cost 3 Ender Pearls and contain only one item. It only yields items that state that they must be obtained from an Ender Chest. Watch an opening of an ender chest here:
Special Event Chests
Special event chests are limited time chests which are only available for certain events such as the Spooky Event, the Winter Event or the Harvest Event Currently, there is a small turkey chest and a large turkey chest which can be unlocked for 250 Runic. Watch an opening of a large turkey chest here:
Large Pumpkin Chest: youtu.be/ZQ_O32Fs658
Large Turkey Chest: youtube.com/watch?v=TjN5TLgXTic