Pediasure for 7 month old?

I baby sit for a friend and her daughter had been extremely fussy lately. She has also had severe diarrhea for almost 2 weeks. I asked her if she has taken her to the doctor, she said she called her pediatrician and she said as long as there is no fever to just give her pedialyte. Am I crazy or are pedialyte and pediasure completely different? Because she showed up at my house today with pediasure, won't this make baby have an upset stomach?