TT's meta is a bit less rigid than SR's. There's the jungler meta and the support meta (alternately called double jungler). Jungler meta is as you'd expect: one guy in each lane plus a jungler. Support meta has one guy bot plus duo top. The player who's not support brings Smite.
Basic team comp consists of a Mage bot, Fighter or Marksman top, and a Tank support/jungle. From what I hear, NA favors junglers, and EU favors supports. There's strengths and weaknesses to both styles, so it mostly comes down to preference.
Try checking the Shadow Isles site if you want a more in-depth explanation. It's a little outdated, but most of the information is still relevant.