In hardwood logging terms those "generally" speaks to lowland vs highland. Lowland getting more water making for a faster growing tree.
A really good example is "swap ash". Swamp ash is not a species of ash it just means its an ash that grew in a wet area. The growth rings of swap ash are spaced further apart thus making the lumber less dense and lighter. Highland ash also called hard ash or sometimes called ball bat ash grows where its less wet like on top of a hill, bluff or the upper part of the side of a hill and its growth rings are closer together making it more dense and heavy.