For starters, the size of the block size of bitcoin is capped at 1MB, whereas the size of bitcoin cash is capped at 8MB.

https://qz.com/index/1044685/bitcoin-split-what-is-the-difference-between-bitcoin-and-bitcoin-cash/

Bitcoin users will experience very little noticeable difference on the front end when using either currency. The main difference is that given equal hash rate bitcoin cash will allow for around two million transactions per day, whereas bitcoin with a 1MB block size will only allow around 250,000 transactions per day. Bitcoin cash allows for more transactions per second which means faster payments and lower fees.

https://www.bitcoin.com/info/differences-between-bitcoin-cash-bcc-and-bitcoin-btc

Adoption is the main issue though.