Tim's answer is basically correct: the situations aren't all that comparable and Russia is more cut-and-dry the aggressor than Israel ever was in any of its wars with its neighbors. And Western countries have not shied away from condemning Israel when in their view it has overstepped.
But to give a realist perspective, there is the simple fact that Russian expansion directly threatens the security of Western nations in a way that Israel realistically never will. NATO is implicitly an anti-Russia alliance, treaty-bound to wage war if one of them is invaded. Russian control over Ukraine is troubling because it gives Russia a corridor of attack if it wished to wage war on a number of NATO states like Poland and Hungary. And Russia's demand to withdraw is that NATO agree to never add another member, which would of course directly impact their future military strength.
Okay though, you might ask, wouldn't Israel's incursions in Lebanon imperil NATO as well, since those countries are theoretically corridors to Turkey? Well, there is also the matter of future ambitions. Israel has never really expressed interest in controlling territory far beyond the borders of the historical Mandate; even during their occupation of the Sinai and parts of Lebanon they never claimed those as Israeli territory. The most provocative position held by a meaningful number of Israelis is that they should exert complete control of the former British Mandate, plus the Golan Heights and Gaza. There is to my knowledge no contingent in the Knesset who believe that Israel should be the next Ottoman Empire.
Putin on the other hand, along with other influential Russians and media, have made little secret of their desire to return to the days of the USSR and Russian Empire's sphere on influence over Eastern Europe. That would imperil a whole host of current NATO members: Hungary, Poland, Estonia, Latvia, Lithuania, etc. to say nothing of aspirant countries like Georgia. It is simply far, far more likely than Russian troops march on Krakow in our lifetimes than that the Israelis land on the beaches of Italy, even if neither is particularly likely.
tl;dr, the West is more concerned with Russia than Israel because Russia is threatening them, and Israel isn't. There are other high-minded reasons, but that's the simplest reason.