collision types can be used to make all kinds of complex interactions like using a grapple on certain surfaces only. The three types unreal uses are block, ignore, and overlap the only way to make two objects to actually collide without passing through is to set both to block each others collision channels. Overlap and ignore both allow objects to pass through each other the difference is that an overlap can be used to access any information of the object being overlapped or to trigger some event.
