Are the UC seats different widths on different planes/places? eg the seats in the nose section of the 747 seems to be wider than those upstairs or on the A340-600...
They are indeed. Not sure if the actual seat is any wider or not but the distance between the 2 'walls' of each UCS on the A346's and upstairs on the B744's is narrower than the UCS seats on the main deck of the B744's.
The other difference is the size of the retractable arm rest, much smaller and too far back on the A346's and B744 upper deck.
The UCS on the upper decks are supposed to be longer when in bed mode but I've never noticed much difference.
Regards