Hopfen is right, especially when they're young - first/second year. Once they're established the foliage pretty much takes on the characteristics of that particular variety although you'll have some different leaf types on different locations of the same plant. Once mature, cone shape combined with leaf shape will get you closer to nailing down the variety. Also, with the Redvines, I suppose the amount red coloration along the vine has to do with where they're grown. Mine are usually just tinged with red along the points of the vine where the climbing hooks are located. Lots of variables to look at. I just grow and have fun with it!