What does "easy" and "hard" mean? Approaching the range? Matching the pitch? Sustaining it for a time?

There are not many tasks that can be cut-and-dried as universally "easy"/"hard". "The Star Spangled Banner" is a more challenging melody because of its wide range. Also, because it's often sung solo, with minimal accompaniment, to huge crowds.

If I were singing falsetto notes, I could probably launch into the range, but could I match pitch and harmonize without AutoTune?