Push - As the name implies, a push subscription pushes data from publisher to the subscriber. Changes can be pushed to subscribers on demand, CONTINUOUSLY, or on a scheduled BASIS. 

Pull - As the name implies, a pull subscription requests changes from the Publisher. This allows the subscriber to pull data as needed. This is USEFUL for DISCONNECTED machines such as notebook computers that are not always connected and when they connect they can pull the data. 

Push - As the name implies, a push subscription pushes data from publisher to the subscriber. Changes can be pushed to subscribers on demand, continuously, or on a scheduled basis. 

Pull - As the name implies, a pull subscription requests changes from the Publisher. This allows the subscriber to pull data as needed. This is useful for disconnected machines such as notebook computers that are not always connected and when they connect they can pull the data.