Crimea was a referendum and Eastern Ukraine separatist rebels. Extent of russian involvement aside, there is a difference between that and an all-out invasion.
They occupied the territory first and then conducted the "referendum" to make it "legal". Don't buy this horsesht.
Ok stop. This isn’t intellectually honest argumentation.
There have not been any free/observed/internationally recognized referendums on Crimea. Most importantly, the referendum wasn't with blessing from Kyiv.
There was an annexaction which was partially done with military means and partially through a mock referendum. Both of those are blatant attacks on Ukrainian soverieignty.