FTA = Free To Air = Unencrypted and freely available
FTV = Free To View = An expression originally used to describe B
SkyB Channels that are Encrypted, but which UK Licence holders are entitled to view without Subscription. ie Card required, at small one-off cost (or an expired Subs Card, although the recent Card change will put the mockers on that avenue for a while)
The FTV Channels are Encrypted because it is the only way of restricting viewing outside the UK (allegedly!) as they are not on the Footprint restricted Astra 2D.
At it's simplest, you need a
Sky Box for FTV Channels (there are other solutions with more complex kit, but a Card is still required), but any generic Digital Satellite Receiver can get FTA. Then there is the issue of EPG Data: You can get full Prog Info etc for Channels that are formally part of B
SkyB or of Freesat, but only Now and Next Info when using a generic Receiver.