The Subaru Impreza is a compact-class automobile manufactured by Fuji Heavy Industries, the holding company of Subaru.
Sales for the Impreza model count for roughly 33% of the total Subaru car sales according to 2013 sales figures. (Data from Autozine)
The Subaru Impreza was introduced to the market in 1992. Prior to creating the Impreza, Subaru’s compact car was the Subaru Leone. The manufacturing went through four generations from 1992 to present. They described in great detail on the wikipedia page for the Impreza.
The sedan is the 4–door model.
This is also called the 5-door model. It has a large cargo space in the back which is accessed using the fifth door.
This is the 2-door model. It’s usually smaller and sportier than the sedan.
WRX “World Rally eXperimental”
The early Impreza WRX were developed in collaboration with the Prodrive British racing team. This started a healthy competition between Subaru and Mitsubishi. The WRX won the World Rally Championship (Manufacturer) in 1995, 1996 and 1997. It’s numerous driver also won WRC in 1995, 2001 and 2003.