Terraria is a similar style to Minecraft but there are more blocks, bosses and different features. If you have read my Minecraft post I suggest you read it because most of it is the same.
There are lots more bosses than Minecraft bosses have lots of health and damage to summon a boss you will need to gather materials witch are hard to get. But if you do defeat the boss you get lots of epic loot witch can be helpful for you to progress in the game.
there are millions of blocks in Terraria all different blocks you can place them walk on them and stand on them they become useful when building buildings you can craft blocks with other blocks like stone into stone bricks.