The difference is Coinbase clearly announced their position that they will NOT honour Bitcoin Cash ahead of time

https://blog.coinbase.com/update-for-customers-with-bitcoin-...

Basically, they said "if your pregnant cow gives birth, we will not give you the calf. If you want your calf, take your cow away from Coinbase and keep it on your own pasture!" And their customers heard it, said ok I'll keep the cow with you, and when the cow gave birth they cried foul.

Sheesh, this situation is 100% predicable because Coinbase announced it ahead of time.