In some ways it is like an alt coin. The difference between a 'fork' and a alt coin like litecoin for example is that the 'fork' shares the same genesis block and transaction history as the original up until the point of the 'fork'.

Practically speaking if you own Bitcoin prior to the fork I believe it means you will then be able to use your coins on both post 'fork' versions. Once the fork happens you will have to decide which version you want to transact on when you receive new coins.

It remains to be seen which version will survive, or if perhaps both versions will.