What is the difference between Vallejo matte medium and matte varnish and wich is the better finish

Simple answer.

A medium is used to mix with another product, IE: if you had a color that was only available in a gloss format and you wanted it as a matt finish, you would mix the matt medium into the gloss paint and it should come out as a matt finish (provided you use enough medium)

Matt medium can also be mixed with pigments to make a muddy slurry to apply to vehicles, and will dry to a matt finish. As well can be used for many other things.

Matt varnish, is just that, a varnish, use it neat to give your vehicle an over all matt finish and to unify all of your painting.

Ok Scott that clears it up I couldn't figure it out thanks