II. Rotation and figure: Uranus 18hrs, Neptune 19.2
III. Composition solar but depleted in H relative to Sun, Jupiter and Saturn. Primarily ices. Enrichment in methane accounts for bluish appearance in upper atmosphere due to absorption of visible red. H2 + CH4 outer layer to 0.2 MBar pressure, H20, CH4, NH3 layer to 6 Mbar pressure, rock+ Fe core.
IV. Thermal structure : Effective surface temperature 50 deg K, 2400 deg K at base of layer 1, 700 deg Kat base of layer. Neptune's luminosity compared to Uranus's luminosity indicates a stronger internal heat source. This difference may be due to larger solar heating of Uranus's upper atmosphere due to its closer distance to the sun.
V. Magnetic fields: not well known, but compression of ices may make them sufficiently conductive for dynamo action.