Both are true and both Palestine and Ukraine needed to decrease their size.
Around half for Palestine compared to their 1945 borders
and around half for Ukraine to Russia,
further land can be claimed by Hungary, Slovakia and Poland.

The difference is is that for Russia

1. Russians are already living in Ukraine because their parents/grandparents never left.
2. They wanted to vote to separate from Ukraine in Donbass but were shot at the voting booth, even killed.
3. Russia was open to discuss where the new borders would stand, but Ukraine demanded Crimea back where 90+% of the people voted to leave Ukraine.

Israel on the other hand

1. It's all Euro-import.
2. No one gets to vote and they kill everyone not Israeli and bulldoze/bomb their homes. They kill every man, woman and child. Israel genocides like Nazi Germany, except worse, because they kill everyone of every country it has so far invaded.
3. Israel demands the entire Middle East. Multiple Arab nations that have no Israeli history whatsoever.