"Green card" literally refers to US permanent residency cards; it's called that because the physical cards issued by the US are/were green. "Other contexts" are riffing on actual green cards as a metaphor, and if speakers in other contexts want to talk about legal specificities, they should use an accurate term...
A green card is literally not a visa in US Law.
In other contexts, it literally is.
"Green card" literally refers to US permanent residency cards; it's called that because the physical cards issued by the US are/were green. "Other contexts" are riffing on actual green cards as a metaphor, and if speakers in other contexts want to talk about legal specificities, they should use an accurate term...
It’s a type of visa with benefits afforded a more temporary form.
A green card like a visa can be revoked. Citizenship gets a bit more interesting with the current administration.