From what I understand, the first assassination it wasn't clear the shooter particularly hated Trump. Sounded more like a school shooter. If anyone has seen reporting otherwise I'd be interested to read it.
Wait. Cmon dude. Trump says "fight" and people scream stochastic terrorism, this guy says you're free to kill Trump if you're not a coward and you're like "naw, that's just poetic license?" Don't be obtuse.
Trump is directing an audience of his supporters to fight, while this is a nobody tweeting at an entire country letting them know they are free to assassinate him. I actually do see a difference.
Specifically, it was directed at Iran and a compitulation to a previous political stance. He is also just some random dude and not a "billionaire" with an actual audience.