Let's see...
IF it was so that they would be otherwise identical but;
- Sound quality would be bad on Watershed and good on Orchid, etc.
- Lyric themes would be more blackmetallic on watershed etc.
- etc.
So then;
Watershed
Pretty revolutionary for (almost) blackmetal album.
Ghost Reveries
A great album too, still not really great quality.
D&D
Would be pretty much the same stuff, except with abit not as good production.
BWP
The same album.
Still life
Would be about as good as Deliverance, I mean liked as much by fans.
My arms, your hearse
Almost the same album but with better quality, some slight changes in music, maybe not as much growling.
Morningrise
This fits pretty well on the place of GR, almost same album but with "better" lyrics and ofcourse much better quality.
Orchid
This would be concidered kind of a style change, one album that some people like and others dislike. Actually it would be change that started already with Mr.
Oh, and Watershed would have much more growling, and Orchid much less.
At the side of that, To bid you farevell would be in GR, and possibly Isolation years in Morningrise. Orchid might have a few songs about the death of that girl then.
This speculation is fun.