As the others said its a fork, the reason they split because of a disagreement in the direction of the BCH coin.
Roger Ver is the main driver behind ABC and they feel BCH is fine the way it is, no need for radical change and want it to be an electronic form of payment for day to day use
While Craig Wright is the big backer of SV and they feel they want to overwrite the network scripts of Bitcoin Cash and increase the block size of Bitcoin Cash from 32MB to a maximum of 128MB, all of which are expected to increase network capacity and scale.
Its basically a disagreement on the best way to improve the network
Thank you my friend for detailed explanation