Without getting into political details, they are two completely different situations, it simply is a matter of how the media packages those stories and how the people consume those stories based on social comformity.
Simply put, anything that seems like the new "thing" to support, or "trendy" to follow, or "fair" to protest about, will get people to start changing their profile pics with that flag, putting stickers on their cars, and adding it to their social media. Are they well-educated on the situation? Do they truly understand it? Or even genuinely care for it? Nope. Just what the media has packaged for them, and what their friends and family say about it.
But hey, it is the new "thing" to support so let's all sing kumbaya and protest by posting as many stories about it as possible.
The US has wrongfully invaded sovereign nations many, many, many times before. But the narrative will always be that Russia is the bad guy and the US is the good guy. So it always depends on who is doing the invading and what the media tell you the reason is for invading that sovereign nation.
Effectively, Ukraine will always look like a good cause to cry for.