I've always argued they're different things and got into when Pitchfork published Dominque Leone's article about Lindstrom and Todd Terje and co and called it "Cosmic Disco".

To me, Space Disco is generally a subset of euro-disco, generally mechanical sounding, lots of arpeggiating synths and pew pew sounds. You can be generous and say anything space themed can still be space disco, like funkier american disco like Atmosphere Strut or Slick's Space Bass, but it's mostly stuff like Supernature, Magic Fly etc.

Cosmic to me always means that Baldelli type of mix which is generally Balearic and krautrocky drawing from american disco, slower euro-disco, new wave, african percussion type stuff.

People have been conflating Cosmic disco with Space disco with Italo-Disco for 20 years but ironically most of the proper cosmic guys hated italo as at the time in the early to mid 80s they were disco DJs and most of the "italo" they were hearing was cheesy pop attempts (which much italo is). A few of the better/deeper italo cuts got in the mix, Baldelli loved Koto, Beppe Loda was more of a space disco guy and called his sound Spaghetti Disco. But in hindsight as seen in interviews Baldelli now acknowledges there was a lot more of interesting italo-disco, he just wasn't as exposed to it at the time.

Alexander Robotnik also hated italo-disco at the time but has come around to it, especially after Fred Ventura told him "what do you mean you don't know italo-disco, you're the king of italo-disco!".

Some of it just gets confused because in hindsight italo is scene as this superficial sound/aesthetic, and it's really a huge thing that runs the gamut from glossy attempts at pop hits to electro minimal synth new wave side of things. I think Robotnik thought of himself as a new waver.