I'd argue that they're all types
of cruisers, each designed with a specific purpose. The Constellation
might be a Deep Space Cruiser, for example. The Miranda
might be an Interdiction Cruiser. And the Constitution
a good ole fashioned Heavy Cruiser.
Of course, we might also want to factor in the idea that each class's mass might be different owing to different amounts of open space. Each of those hangar doors on the Miranda
might feature an empty volume similar to the one found aboard the Enterprise
in TMP, making each of the former more hollow while still comparable in size.