They do. As tanker mentioned above, Vallejo Model Color is thicker, much thicker and has some great (IMO) self-leveling properties for brush painting. (if it's too thick, many folk thin it a tad with distilled water. I've done this myself)

Model Air is advertised as ready to spray out of the dropper bottle, though many if not most add a bit of thinner (and I'd stick with Vallejo thinner only). I go both ways.

Model Air does not brush well at all. It is too thin. It works great for small touch-ups, and I've left it on the pallet for a while to thicken up a bit for larger jobs when I have no corresponding Model Color color, but it's still not the best.

My two cents anyway. Others might have more info for you.

Forgot to mention this earlier but do Model air and Model color have significant differences between them ?

Great! I'll see if my LHS has Vallejo paints.

I also agree with nathan about Vallejo for brush painting. You can find them in sets for certain genre witch saves a couple bucks over buying individual bottles. Mike

I agree with Nathan about Vallejo. Model Color for hand brushing and Model Air for airbrushing are the best IMO. But I do also use thinned Tamiya but only airbrushing.

Use Lifecolor or Vallejo for handbrushing. Anything else will leave you frustrated. Gunze paints airbrush the best imo.