There are two types of regulations for sports betting in the United States. In-person sports betting and mobile sports betting.
In-person: going to a bookmaker to place a physical bet. This can be at a brick and mortar bookmaker or retail location. In some states it is also possible to bet on sports in casinos.
Mobile sports betting (aka online sports betting): this sports betting that takes place online at a betting site or online sportsbook. This can be from your desktop computer or through a betting app on your cell phone.