1) unlike Trump, Clinton did not make a shout out to a specific audience ("you second amendment guys'), meaning Trump basically issued a call to arms, and Clinton didn't;
2) as the first serious black candidate for President, Obama was already being targeted by hate groups (he had received a Secret Service detail an entire year earlier than any other candidate, ever, because he was already the target of hate groups), so Clinton was stating the already obvious, rather than suggesting someone "do something."
Also, in contrast to Trump, Clinton apologized for the remark. Trump has not apologized, but instead blamed everyone else for misrepresenting what he said, and has done what he always does - double-down on his bullshit.
And finally, the meme totally mangles the English language. Okay, that's just marketing to the illiterate target audience - "what happened don't happen" - the word is "doesn't" you morons (or should I say "morans"?).