What is Bitcoin Cash ?
Key differences between Bitcoin and Bitcoin cash are in the philosophy rather than the technology. Currently the BTC community is focused first on keeping Bitcoin decentralized so that it can remain as a public, permissionless, highly censor-resistant network that anyone in the world can use and build on top of. Fast, cheap payments are a secondary priority.
In contrast, the BCH community is focused first on enabling fast, cheap payments over the network. The BCH community believes that by focusing on these features, BCH will onboard more people and this increased adoption will foster decentralization.
Bitcoin Cash Split from Bitcoin
Bitcoin the Block size is currently limited to 1mb and has adopted Segwit, which makes the network ready for lightning network. BCH supports larger block sizes and has not adopted Segwit.