When viewing a player profile in the mobile app version, I believe desktop Flash version players will have a yellow or gold "WGT" pennant to the right of their name, and if they're online there will a white check next to it. Please let me know if I'm totally wrong on this.
Also you can tell by their apparel whether they primarily play the mobile version if they have buffed sets of gear used in and awarded from one on one multiplier play.