[rory096]

This is of course not surprising - in the long run all difficulties (for similarly hashed coins) should trend towards equalizing profitability lest they create an arbitrage opportunity. The driving factor in the grandparent's case was the short-term spike in BCH after it was listed on Coinbase.

[nosuchthing]

Not entirely. There was a flaw/feature in the difficulty algo for BTC Cash that allowed miners to generate a significant quantity of blocks very rapidly.

https://news.bitcoin.com/bitcoin-cash-hard-fork-plans-update...