To simply summarize the ops question.
Remastered does mean that someone has changed the original recording release in some way shape or form.
Hopefully for the better as per Steven Wilson's work on King Crimson, Jethro Till etc.
However not always can you count on a remaster being an improvement on the original, different always for sure though.
A rerelease on the other hand might just be that, a straight release of an out of print album with zero changes made .
Although even that is not likely as record pressing and vinyl mixes all have changed so nothing from say 1970 original is going to sound the same as a rerelease in 2020 say.
Simple it is not!
Remastered does mean that someone has changed the original recording release in some way shape or form.
Hopefully for the better as per Steven Wilson's work on King Crimson, Jethro Till etc.
However not always can you count on a remaster being an improvement on the original, different always for sure though.
A rerelease on the other hand might just be that, a straight release of an out of print album with zero changes made .
Although even that is not likely as record pressing and vinyl mixes all have changed so nothing from say 1970 original is going to sound the same as a rerelease in 2020 say.
Simple it is not!