A regular spike is one of the rarest obstacles in the game, but it is oddly shown first in the tutorial along with the Moving Spike.
A moving spike is a spike which is moving, and is much easier to pass then a Regular Spike.
A lava jump is a common obstacle that you have to jump over.
An acid jump is the same as a lava jump, except made of acid. It is slightly rarer then the lava jump.
The Wood Slider is a wooden slider you have to slide under with Tool 4 (Fall).
The Lava Slider is a slider made of lava you have to slide under with Tool 4 (Fall).
The Acid Slider was a cancelled obstacle that was made of acid you have to slide under with Tool 4 (Fall).
Stairs are obstacles that help the player progress to move up or down.
Tightropes are thin platforms you have to walk across.
Lasers are obstacles you jump over. They were originally meant to be slid under.