A Gas station/Filling station/Petrol station

There are generally two types of filling stations in the US: premium and discount brands.

First, filling stations with premium brands sell well-recognized and often international brands of gasoline, including Esso, Exxon, Chevron, Mobil, Shell, BP, and Texaco. These stations often charge higher prices as well. However, the stations also have numerous locations and more available pumps. For ease and convenience, many of these stations have fully automated pay-at-the-pump facilities. Premium gas stations tend to be highly visible from highway and freeway exits, as they use tall signs to display their logos.

On the other hands, discount brands are often smaller, regional chains or independent stations, offering lower prices on gasoline. These discount gas stations are often located well away from highway and freeway exits; many are tucked away in obscure commercial and residential neighborhoods. Examples of discount gas station chains in the USA are Valero, Rotten Robbie, and USA Gasoline. Lower-priced gas stations are also found at some supermarkets (Alberstons, Kroger, Safeway, and Vons), convenience stroes (7-Eleven) and discount strores (Wal-Mart) and warehouse clubs (Costo, Sam's Club). At some stations (such as Vons, Wal-Mart, Costco, BJ's, or Sam's Club), consumers are required to hold a special membership card in order to receive the discounted price.

In the United States and Canada, federal, state/provincial and local sales taxes are usually included in the price. In the United States, the states of California and Hawaii typically have the highest gasoline prices. However, the prices for gasoline in the United States are among the lowest in the industrialized world; this is principally due to a difference in taxes. While the price of gasoline in Europe is more than twice that in the United States, the price of gas excluding taxes is nearly identical in the two areas.
These are partly cited from anwers.com