Typically, size of the rooms, quality of furnishings, quality of services provided- and the price.
There is no set number- It varies from one hotel to another. I know of two in Hawaii about a half mile apart- one has 600 rooms, the other has 12.
About 800 square feet, plus a second bath and a powder room, plus a thousand dollars a night.
Management = You build a hotel and lease it out to a professional hotel organisation who manages it for you Ownership = You own a hotel and decide whether you manage it yourself or have it managed...
The Avalon Beach Hotel in Bournemouth is considered a luxury hotel and has won awards on Tripadvisor in the UK and Europe.