Freeview = Channels you get using an aerial. They are not on satellite or Virgin. They are also known as Terrestrial channels.
FreeToView (FTV) = Channels that requie a subscription card with valid entitlements. You do not need a subscriptoin from provider, just a card with entitlements. Your box has to be set to read the card.
FreeToAir (FTA) = You do not need a card. This applies to services on Cable (Virgin), Terrestrial or Satellite
Note: Just because a channel is FTA on Terrestrial, it does not mean it is FTA on Satellite or Cable.