If you have a closed loop, whether it's a single eye or held together by a fisherman's knot, you can only tie a prusik knot as far as I'm aware. If you have an eye 2 eye, you can tie additional knots like the Distel, Blake's, Schwabisch hitches and probably others I'm not aware of.
Is there a need to have anything other than a simple prusik loop if the intent is a fall restraint? Thanks.