The problem with this line of thinking, as well as the point the OP's meme makes, is that it's drawing a line between the two in the first place, when in fact there can be significant overlap.
A quick dictionary lookup yields this for terrorism: "the unlawful use of violence and intimidation, especially against civilians, in the pursuit of political aims." Note that "especially against civilians" doesn't mean it has to be, just that civilians being involved makes it a stronger case.
Now, you may have already spotted the issue, but here it is anyway: this is an incredibly broad definition. Laws don't bind those in other states, so ANY act of violence or intimidation is unlawful.
So...freedom fighters fight using violence, against the laws of the country that claims sovereignty over them... so they're terrorists. Full stop. This doesn't mean that we should or shouldn't support them, it just means that the definition of terrorism is pretty useless.
It DOES mean the distinction between them is useless.
Which is my point.
If you chop the heads off people who are not even Israeli, or torture infants in their beds; you are not supported due to the acts against people completely outside any who oppose you.
I don’t support Hamas because they kill innocents, for no benefit to the people of Palestine, but only because they want violent death to Jews.
I don’t support Israel in their campaign because they kill innocents, for no benefit to the people of Israel, but only because they want vengeance.
Both actions are pure barbarism. Anyone able to look at pictures of tortured and mutilated bodies of innocent people and think “ these people are to be supported” is delusional, morally bankrupt, and failing the test of integrity to purpose.
Terrorist is a political designation that has no clear definition. It is used as a catch-all term for undesirables as a way to commit war crimes indiscriminately.