As described by URI for their bulbs:
Actinic Bulbs
The Super Actinic R is a lamp which is an excellent source of long wave ultraviolet radiation, peaking precisely at 420NM closely resembles that of the blue chlorophyll absorption peak utilized in photosynthesis. It's benefits at 7100 Kelvin help enhance the fluorescent colors of Fish and Invertebrates
White Actinic Bulbs
The Actinic White is the first of its kind, contains a rare mixture of triband and actinic phosphors for great color rendition (5000K) and a special actinic phosphor (7100K) which provides a realistic and life supporting spectrum needed by live rock, coral, anemones and related marine life. Common Nicknames: 50/50 bulb, 10K bulb
AquaSun
Achieves a wide spectrum color rendition wich greatly enhances the color of tropical fish. Aquasun's unique blend of triband phophors provide additional color temperature (5200K) for your fish/reef system.
Recommend Combinations:
2 bulb systems:
Reef Mixed - Actinic White & Super Actinic
SPS Coral Reef - AquaSun & Super Actinic
Fish Only - AquaSun & Super Actinic
3 bulb systems:
Reef Mixed - 2 Actinic White & 1 Super Actinic
SPS Coral Reef - 2 AquaSun & 1 Super Actinic
Fish Only - 2 AquaSun & 1 Super Actinic
4 bulb systems:
Reef Mixed - 2 Actinic White & 2 Super Actinic
SPS Coral Reef - 3 AquaSun & 1 Super Actinic
Fish Only - 2 AquaSun & 2 Super Actinic
Hope that helps