Let's see.. Bitcoin Cash only increased the block size.
Bitcoin Gold only changed the mining algorithm.
Bitcoin Private will only increase the block size slightly and add Private transactions feature to Bitcoin.
Bitcoin Diamond increased the block size and maximum supply and added some encryption?
Bitcoin 2 adds Swift TX feature, Private transactions feature, block size increase, faster block interval (= faster transactions), prune the blockchain so that new nodes can join easier, Proof of Stake instead of PoW etc.