Vanity bitcoin addresses are just like any other bitcoin addresses, but they are unique in a way as they contain some custom text like 1BTC............ .One just uses the private key to add the address to his wallet.
There is no additional advantage of having one, but they just look cool !
As the user uses split key generation, so there is no risk of loosing funds as he only has half the key only.
Also do not trust any site that generates the"whole" private key as they are sure to scam.