The "org.eclipse.emf.compare" feature is the minimal core of EMF Compare, which doesn't even depend on Eclipse (see the wiki for the dependencies of this core). edit does not have its place there. We made the choice of not having an "ide" feature containing the edit but not the ui in order not to have too many features (we already have a handful).
"org.eclipse.emf.compare.edit" is provided by the "org.eclipse.emf.compare.rcp.ui" feature if you wish to have fewer dependencies... though that still depends on some UI things.
If you need to have the core of EMF Compare along with its edit support, but without any UI dependencies... we're short one feature. You could depend directly on the o.e.e.c.edit plugin though: p2 will be able to take only that plugin instead of the whole ui feature when installing your product if you do so.
The fact that "core" does not depend on eclipse was not the main point, I was only mentionning it . The core is what users (and we do ourselves) can depend on if they only need to programmatically compare models (within unit tests for example).
The real issue is that "edit" really lives in another "world"... it does not really belong in ide.ui, nor does it belong in the core. The missing feature(s) are o.e.e.c.ide and o.e.e.c.rcp... it would not cost much to add them to our repository, but that does little more than multiplying the available options and confusing the end-users. Many users won't even realize the difference between our "rcp" and "ide" plugins, nor do they care about "SDK" ones...
Could you raise an enhancement request about this? It might be interesting to look at how we could categorize further or provide additional features while still "hiding" them in some way (no category for example).