An implied easement is an easement that arises from an implication of an intended grant of easement which is unwritten. It would usually require going back to the inception (1926) and trying to divine those intentions at that time.

A prescriptive easement does not assume that an implication exists, only that the legal requirement for prescription exists. Your mileage may vary depending on your state case law. For you, the difference, if any, is probably of no consequence at this late date.