: Some here seem to use these two terms to represent different things.

: What is the difference, or is it just a difference in the way people believe the same event turns out?

well, first off, there are different models of what a wormhole is. There is a model of a wormhole whos enterance is that of a black hole; thus having a singularity. Another type of wormhole is one that its mouth is either held open by centrifugal forces or 'exotic matter'; hence, without a singularity.

I personally support the notion of the existence of wormholes without the presence of exotic matter. ie. the black hole (non-traversable) type and the centrifugal type. I believe exotic matter is a relative expression of gravity force between two points; that is, it impossible to have in true existence antigravity.

How can one observe antigravity in a universe who's bacground is that of gravity. It is all relative.

To visualize this, imagine the "rubber mat" concept once again. Standard gravity supposes a 'bowling' ball on a rubber mat therfore distorting and leaving an depression in the mat. Antigravity, or exotic matter would result in the observance of the rubber mat displaying an inverted depression; a "pimple" :)

I believe this is strictly impossible and out of the realm of space/time continuum due to one important reason. The concept of time reversal.