Arab citizens in Israel proper do face discrimination, but calling it "apartheid" is, to put it mildly, hyperbolic. Under apartheid, South Africa never let blacks into parliament and even revoked the citizenship of blacks. Nothing of the sort goes on in Israel proper. Are Arabs in Israel treated the same as Jews? It's obvious they are not. But not all discrimination rises to the level of "apartheid."
And at any rate, the Arab citizens of Israel are treated much better than Palestinian refugees in Syria, Lebanon, and Egypt, where even after generations in the country they still do not have citizenship and are only allowed to work in a few select occupations and must live in the refugee camps. But no one ever says Syria, Lebanon, or Egypt practice apartheid. I wonder why?
As for Israel's actions in the Occupied Territories, that's a separate matter. Still not one rising to the level of apartheid in my opinion, but it's plain that Israel is not always in the right as many politicians would have us believe. But if you want a just, peaceful solution to the dispute the answer is not to run around screaming "apartheid." It's factually wrong and hyperbolic claims like that de-legitimize the cause of Palestinian statehood in the eyes of many people who otherwise would be allies.