My baby rarely spits up but when it's because hes eaten too much it smells like straight vomit. Sorry to be gross but reflux spit up kinda just smells like formula/breastmilk but the eaten too much stuff is raunchy smelling in my opinion lol. Obviously this is just an observation based on my baby
Usually, if it's them eating too much, it won't be chunky, just look like regular formula...When my daughter eats too much, she'll throw it up within a half hour and it looks/smells just like formula.
Re: spitting up. sorry lol