I think what people are comparing to apartheid South Africa, or at least what I would compare to apartheid South Africa, is the entire picture of Israel's treatment of Palestinians in Israel, Gaza, and the West Bank.

If you're speaking specifically about Arab Israeli citizens living in Israel, you might be able to make the case that they have something approaching equal rights. And that the legal system and government treats them nominally equally. But once you set foot in the West Bank or Gaza, this argument falls apart completely.

For the people who live there, Israel (and here I'm speaking pretty much exclusively about the Israeli government and the settlers) are unequivocally the "bad guys." It's not just the American Left who thinks this. Pretty much every international human rights organisation in existence is clear on this.