Your confusion with the bulb spectrum and its correlation to coral growth is understandable. One of the predominant problems with lighting is not necessarily the bulb spectrum but often times it is the name of the bulb. I'm going to give you one example, but it is an unbelievably common problem from manufacturer to manufacturer.
D & D Giesemann bulb - AquaBlue+ is not a blue bulb. It is approx. 11k and
crisp white. This is the bulb I use for my daylight, or what you seem to be referring to as my 'growth' bulb. So if someone were using (all D & D for this example) 3-AquaBlue+, 2-Actinic+, 1 Pure Actinic it would appear to the untrained person that there were no 'daylight' bulbs above this tank, when in fact there are three. Very confusing, I agree.
FYI: D & D also manufactures what they call a Midday bulb. This particular bulb is approx. 6k and appears very yellow to the naked eye, not an aesthetically pleasing bulb but also recommended by the manufacturer for growth (not by me
).
In order to become more in tune with the bulb names vs appearance you need to use various brands, various spectrum, and various combinations to see which combination works best for you. It really is a very personal preference when selecting bulbs.
Hope this helps,
Russ