The color represents a players game activity. The more red it is, the more moves the person has made...
A plain star without the little wings represents original pawnstars. These were awarded to members who made a purely voluntary financial contribution to the owners of the site (Chris and Russ) to help keep the site running.
Later, members were offered the option to pay an annual or monthly subscription and anyone who does that is identified with a star with wings. (Many of those with the original pawnstar status have also paid for subscriptions, so their star has wings as well.
Pawn stars are allowed to play unlimited games and enter tournaments.
Those with free memberships (no star) can only play ten games at one time, and cannot play in tournaments.
The free membership allows anyone to join this site and play for as long as they like. One benifit of this is they can try it out for as long as they want, and hopefully decide to become a paying member!
Hope that helps. (You can click on a star icon and get some of this information)