Yet another example of the difficulty of separating the airframe from what a specific airline does with it. The two aircraft are much closer to each other than what the airlines choose to do with them. Very few of the factors that anyone has mentioned are inherent in one airframe or the other. The main one is the forward-facing windows on some versions of the 747 - and those only matter if you happen to be in the right seats. Another inherent issue, not mentioned so far unless I missed it, is that that a 380 can be boarded and unloaded more quickly through its two doors than a 747 can be with one - and woe to the mobility-limited 747 passenger who finds out after boarding that he or she has a seat in the upper deck! (A human check-in agent might catch that, if he/she knows about this issue and is paying attention, but lots of passengers don't check in with a human agent.)