lrpwd

Hi, All:

I want to buy a seat for my one and a half years old boy. I check the flight price and I am a little confused. I search on Expedia, it has a choice as "infant in seat" which is cheaper than child ticket, but another search engineer, vayama, only has a choice of child ticket. I don't know which one I should buy, any difference between these two? Anyone has a same experience? Also, for infant in seat, do I have to buy a car seat for my infant?

Thanks a lot!