Bitcoin Cash (BCH) is an upgraded version of the Bitcoin Core software. It was released on August 1st, 2017, when BCH hard forked from Bitcoin. The technical difference between the original Bitcoin software and the one of Bitcoin Cash is an increase of the block size limit to 8mb. This effectively allows miners on the BCH chain to process more payments per second.
It also allows faster, cheaper transactions and much smoother user experience. Bitcoin Cash was created to bring back the essential qualities of money present in the original Bitcoin software. Over the years, these qualities were filtered out of Bitcoin Core and progress was stifled by various people, organizations, and companies involved in Bitcoin protocol development.