A "barrel roll" is a rolling manoeuvre that is quite lazy and gentle and describes a path that you could imagine being around a barrel in the sky. A 4 point roll describes a roll maintaining the same height and direction but stopping (momentarily) at each 90 degrees of the roll ie after the first stop you are "knife edge" - the second stop you are inverted etc etc. There is no such thing as a "4-point barrel roll".