The gentle ease uses a different set of proteins I believe to be easier on the stomach. The infant ones use less broken down proteins than the newborn ones because at that point their stomachs can digest them better. At least that's my understanding. I highly recommend calling Enfamil or asking through their FB page though - their customer service is stellar!
We get Enfamil delivered from Amazon about once a month. The expiration date is always a year or more away. Sometimes we get one that is from the same manufacturing lot as the previous month's delivery, but still a year or more away.