A Web Series is a TV Show that is not of a normal length and can be anywhere from 3 minutes or longer for each episode. A Web Series is aired on the internet or online and cannot be seen on Broadcast or Cable TV. Over the years networks like Sparkk TV have begun to sprout up that specialize in airing web series in their own TV Network like environment or hub and are known as Online TV Networks or Web Series Networks.
A Webisode in essence is an episode of a WebSeries. They can be called a Webisode because they are again shorter in length than standard TV episodes.
A Web Movie is a movie not of normal length and is the Movie equivalent of a Web Series.