What do you call a house with two floors?
Likewise, what do you call a house with one floor?
A bungalow is usually a small one floor house that can be expanded by adding a bedroom down in the basement or up in the attic, so it's more the name of a one story house with room to grow.
Also know, what do you call a 2 story apartment?
A 2-story apartment, to me, would be just that, an apartment with 2 floors, typically called a duplex, that can be in any kind of residential building, from a small house to a high rise building. It can be a single full floor apartment or portion of a floor or two and three floors called a duplex and triplex.
Townhouse. A townhouse is a unit in a row of other units that look like houses, attached to each other. Townhouses (sometimes called row houses) are usually 2 or 3 levels tall (each level is called a 'storey').