Bitcoin:
- has all the support from the community, all the miners, all the nodes, all the businesses and merchants
- has the highest price, it is rising, and a solid support behind it, has the highest volume, and is listed on all exchanges and the most trusted exchanges.
- has the best developers that have been working on it for 6+ years and the code is reviewed by thousands of people who check each change and look at the code.
- countries have adopted Bitcoin, like Japan and regulated it and removed taxes on it.
bitcoin cash:
- is an altcoin
- community does not want nor supports it
- miners do not support it
- developers do not support it
- businesses do not support it
- top exchanged do not support it
- countries adopted bitcoin and not altcoins
- the code is rushed, not tested, not reviewed, not trusted
- the change they are making is a fundamental change and will change a lot of things. it is a hard fork and can cause a lot of problems down the line for example in a year if it gets any traction.
- the price is low and dropping hard even before it is released (started at $900 and now it is worth nearly $300) and the release will crash it down to somewhere between $100 and $10
this is just a small number of differences.