I'll actually try to answer the question, something which not many have done I'll make it very clear that obviously I haven't played KSP2, so there's a lot of assumptions for how it might do things, and I haven't played Starfield, so I'm basing this purely on the details in the original post of this thread.
It looks like KSP2 has made a bit of progress compared to KSP1, but I still think the ships produced will be very generic. I don't know if we'll be able to make interesting looking ship through clipping parts, and having parts overlapping as in KSP1. If we can't, that'll make things even more generic. If we can, it's still a poor way to build things. I guess we'll be able to download mods which have new parts in them. But in general, I don't hold out much hope for ship building in KSP2.
The ship building in Starfield looks pretty good. It seems as though you're able to make ships that look interesting and cool, and it looks like you can colour them however you want.
I'd give the Ship Building round to Starfield.
Base building and resources
This looks like it could be great fun in KSP2. I know we haven't seen an awful lot of it, but it was fairly decent in KSP1, and it's supposed to be a major part of the game in KSP2, so I have high hopes for it.
This part of Starfield seems like it could be a bit simplistic? It looks like it's a basic 'select the building you want, then click where you want it'? It also sounds as though you wouldn't be able to set up a base near anything that isn't flat-ish terrain, something which doesn't look like it'd be a problem in KSP2.
Resources will probably be similar in both games. They're there, you have to collect them. Not sure there's much more detail than that for either game?
I'd give the Base building and resources round to KSP2.
Exploration & environment
This is an interesting one. I know people have gotten excited about something that was said in one of the KSP2 videos, about a pixel of light being a system you can visit, but I think that may have been misunderstood. I don't think every pixel of light will be somewhere you can travel. I think there will be multiple systems, and they'll be different and interesting, but I don't think travel between them will be very common. The fact you're meant to travel to a new system, and then set up a new space centre, means that once you're in a system, you'll use that space centre as you would use Kerbin Space Centre for exploring the Kerbol system. I also expect resources to be available in every system, so you want need to transport stuff from one system to another. Again, I don't know this will be how it works, because I haven't played it, but that's what I think at the moment.
The planets that we've seen in the videos so far look amazing. I'd like some features that don't seem to be there, cave systems, flowing water, weather, different surface types and properties (ice should be slippery, boggy ground should be soft and have ships sinking....).
Having said all of that, I don't know what the planets in Starfield will be like either! It looks like there will be other species in Starfield, so that's a plus. KSP2 probably won't have anything other than some basic trees and plants. Starfield says it'll have over 100 systems, and over 1000 planets, so I guess there's some procedural stuff going on. The pictures look pretty good, but I don't see it as anything ground-breaking.
Probably the closest round, I'm going to call this one a draw.
Ship IVA / flight deck / HUD
I'm not sure I'm qualified to comment on this too much, I very rarely (if ever) use IVA mode in KSP. I'm just not interested in it. Not when in space, not when driving rovers. It just isn't something I care about. I don't take Kerbals out for walks other than to plant a flag, drop some experiments, or move from a base to a rover.
So I'll call this a 'no contest' round. Sorry.