I would say that Cherry is closer than Marie-Hélène.
In normal English, you will only hear 'storey' when you are talking about the structure - eg 4 storey building, 9-storey hotel, 3 storey house.
Yes, it refers to the number of floors, but is not synonymous with 'floor'.
When you are talking about the actual level itself, you use 'floor', eg 'my apartment is on the 4th floor', 'the library is on the gound floor and the restaurant is on the 5th floor', 'the lift will take us to the top floor'.