Im planning to build a zip at some point as it goes . Good typhoon parts are quite hard to find strangely which is annoying but yeah the only real difference between the two is appearance, typhs are a bit marmite i have found people either really like them or hate the way they look lol.
And size? Totally differently sized bikes. lol LC on a typhoon is quite bodge even for a 50cc. It's much easier on zips as the make LC ones. As ramo said parts are much easier and cheaper for zips than typhoons.