Minimal. The only real difference is that the juice you make cider from is already at the right concentration to brew unless you're buying concentrates, so you won't have to worry about water treatment or anything like that. You already know how to measure gravity and calculate abv (or you don't care). Add-ins like hops or herbs work the same. You should be able to transition pretty seamlessly to ciders and even wines. It's beers that can be a bit more difficult and involved because they have a cook step.