In addition to what TNG said, it's also helpful to recognize the various motivations behind the outrage for each incident.

Reactions to Trayvon's slaying fell into several camps. The obvious are the polar opposites of terrified black folk protesting "It could have been me" and the vile and proudly racist "good riddance". In the middle however there was another "It could have been me". The people want to be able to protect their property with lethal force, but are scared shitless of fucking up in the process. They basically sided with Zimmerman because they would also like to walk if they incompetently protect their domain and kill a kid armed with skittles and iced tea.

The outrage at Cecil's killing also falls into multiple camps. There's the varying degrees of genuine conservationist view, the entitled-to-kill-all-the-things-for-entertainment view, and then there's the view you're probably most seeing on twitter. It is probably best described as "I'm jealous that someone is able to spend the average middle class annual salary on a holiday" thinly veiled as conservationist.

I am confident that the Trayvon "I might fuck up and kill a kid with skittles" crew and the Cecil "Fuck you for spending my entire annual salary on your safari" crew have a fairly broad overlap.