The names - the logo - the locations - all meaningless.

If you want to define Doubletree start with this - Give me a one sentence description of the brand that tells me what to expect.

A Hilton hotel is an American style, full service, mid-range hotel.
A Waldolf Asotria hotel is an American style, full service, luxury hotel.
A Hampton Inn as an American style, budget hotel with free continental breakfast.
A Conrad is a European style, modern, full service, high end hotel.

A Doubletree is a random assortment of mostly full service hotels some low end some high end with no unifying style but free cookies at check in.