What do lions eat, which cats don't? の意味は？

「ライオンが食べて猫が食べないものは何？」

だそうです。

I sometimes read ABC News website to learn native, sophisticated, and correct English.

This is not a piece of advice to you I'm talking to myself for my practice of writing skills.
Lions can eat their owner if they want to, but cats never want to eat their owner.
owner/keeper should always pay attention to whether lions are hungry.