The actual little chip that puts out the light is the emitter. The strips of leds are just that strips of leds.
The 1w individual leds are in a different class, Im not sure what its called its something like high power emitters, or high output. They have individual aluminum baseplates and some (like most of the cree's) can be either 1w or 3w depending on how you wire them and/or what driver you power them with. When you buy them, you should get info on how to run them as a 1w led
or as a 3w led
. For example I have some Royal blue cree's that are 1w or 3w. If you run them at 3.3v and 350mA they are 1w, and if you run them at 3.3v and 750mA they are 3w. Some other 1w leds are just 1w and cannot run at 3w.
I'd just use 1w or 3w depending on your needs. If you need around 75w of led
lighting, It would be easier (in my experience) to use 25 x 3w leds as opposed to 75 x 1w leds. But it just depends on your tanks requirements. And that light isnt that bad, its just If it was 50x3w leds it giving you the 150w of power it would be much better. That was just done to be the cheapest way possible to say you have led
lighting, kinda like marineland does with their fixtures.