Nocollision is a state similar to ignore with one major difference: it can move. For example, instead of having to make two groups and making the inside group ignore you only need one group set to nocollision.
Also, a nocollision object activates the OnTouch command; a ignore object doesn't. If set as an emitter, they will produce solid objects. Finally, you cannot set an object inside another group to nocollision.
Static |
Frozen |
Ignore |
Static Mesh |
NoCollision |
Show Collision |
No Auto Freeze |
Magnetic |