So, I'm looking through the Magic Items section of the DMG, to decide what goodies to stick in the next hoard and I come across this anomaly. Boots of Levitation are listed as 'rare', but Winged Boots are listed as 'uncommon'. Does that seem reversed to anyone? Levitate is strictly up/down, with no lateral motion possible (except by pulling oneself along a wall or ceiling, etc). Winged boots grant motion on all three axes. The only justification I could see for this would be that Winged Boots have limited duration per day v the Boots of Levitation being at will, but I assert that 4 hours of flight per day is sufficiently unlimited for adventuring purposes. The only person I can imagine that would prefer unlimited levitation over limited duration flight would be a librarian working long shifts.