Whats the difference between a parallel universe and another dimension? Explain
Parallel Universes are like the term says Parallel to ours. They follow the same types of physics rules as ours does for the most part. This is where the ideas of parallel Earths and other stuff comes from.
Other Dimensions could mean two things: One is the Parallel Universe and the other is multidimensions that are higher than ours (fourth, fifth sixth etc).
Of course these are my opinions and ideas as there are string theories and other ideas which are different versions of the same basic idea.
Is it possible to traverse between the dimensions and alternate universes? I think so and that could explain some of the UFO and abduction cases out there.