If you have purchased tokens you can pay a model and ask her to do something in exchange (e.g., remove a piece of clothes).
Hence, free cams give you a chance to watch an adult live show , but tokens give you an opportunity to gain a pretty interactive experience: basically, you are the one to control a girl you see on the screen.
Anyway, it is better to find a site that offers you a wide selection of shows.
Depending on your preferences, you might be satisfied with the very basic type of free live adult web cams that depict ladies who perform alone.
The sites differ in terms of the freedom you have and in terms of your involvement in a show.