The conditional, If four points are non-coplanar, then they are non-collinear, is true:
This is, coplanarity is a necessary condition to be collinear.
The converse, If four points are non-collinear, then they are non-coplanar, is false.
A counterexample that disproves this statement is the 4 vertices of a paralelogram, of course they are in a same plane and are not collinear.