REGULAR OL' BUILDINGS

Buildings are not always famous.
Here are a couple of buildings in Chicago.
These are called residential buildings because they are buildings where people live.
The buildings on the left and in the middle are called "Two-Flats".

The building on the right is called a "Three-Flat".

Residential buildings can be tall skyscrapers or teeny little huts.
Castles are residences for royalty and a shoe box is a residence for shoes.

What is the difference between a two-flat and a three-flat?