Ay, honestly ang Nestogen 1 is more for newborns (0-6 months) kaya kung gaano kalaki na ang baby mo ngayon talaga ang pinagkakaiba, ang Nestogen Classic is more for older babies na. Both are supposed to be easier sa tummy, pero different formulations talaga for different stages, so basta tignan mo lang kung saan age range ng baby mo fits better! A few of us moms actually switched from one to the other depende sa age, and some babies tolerate one better than the other pa, so baka trial and error din talaga para makita kung alin ang best for your little one.