It's about the specific case of Israel. No other nation is claiming territory that was never within its borders.

There are valid arguments on both sides of the Tibet debate. But no one denies that Tibet existed under China's sovereignty for lengthy periods. As a sovereign nation that has existed for a very long time, China has a good argument that Tibet is part of it.

Israel can't make that claim. It only came into existence in 1948. To be sure, the 'Israelites' existed thousands of years before that, but so did other ethnic groups on the same territory.

Now to the point. All the important nations in the world recognize Tibet as part of China. That includes the EU, the USA and Canada. But no nation that I'm aware of recognizes Israel's claim to the West Bank, and neither does the United Nations. Israel is perpetrating a form of ethnic cleansing by populating the West Bank with its own people. Ethnic cleansing is a crime against humanity.