M.K.
With reflux you want to watch with excessive spit-up, crying after being fed, crying when layed down flat, basically anything that can allow those stomach acids to creep back into the throat. If they seem better if they are kept in an upright position I would guess reflux. A gassy baby is more of lots of farts, pulling legs to chest, sometimes you can hear the gas rumbling in the stomach. If it's gas and not reflux it could be the formula or it could be that their digestive system needs a bit more time to mature and will work out the gas issues on it's own. Unfortunetly either scenarios are painful for babies.