Lighting Spectrum

Simple answer is: Plants will grow in any bulb sold in Loew's except maybe a colored one like a green bulb. Certain spectrums are just better used by the plants.
It helps them and they will grow better the more you get those two the 460 and 660 nm spectrums involved in your light system. Some plant are grown in sheds where filter are put over x amount of window panels to cut most of but not all light letting one or both of those spectrums get through to the plants. I have seen pictures of plants grown exclusively under the red lights before.
But know that bulbs that are single spectrum bulbs lack other spectrums that the plant can utilize also.
What are you trying to do/build/get ?
BTW horticulture farms have hundreds of plants and they should know. They are now saying that the 5500K bulbs do better and some shops(horiculture) have them in 2 or 4 ft only now. Better than 6500K.

While spectrum is not totally unimportant, basically as said, anything between about 3,000k and 10,000k will grow plants. Intensity/par is much more important.

Remember that the K number is ambiguous by nature. Not only will a bulb put out light in other spectrum's than what the bulb is called, it's really used to describe a visual color (as far as I remember). It's much more of a description of what you should expect to see, rather than a scientific representation. Many bulbs will come with a graph but that really doesn't matter in practice either.

Making it even more ambiguous, many of us have preferences as well. For example, I love a 10,000/6,7000k combo on a green tank. The more reds in the tank, the further down the scale I want to go. My current tank has a 6,7000/Rossette combo. The overall look is more similar to incandescent/warm white light bulb than it is to a true white florescent tube. You could have never made me believe this combo would look good, and it took some time getting used to but my reds are much brighter than a 10,000/6,7000k setup.

Further adding to confusion. Once you have more than two bulbs, you may end up liking a purple or red bulb in the mix that would look absolutely horrible on it's own. They are often not as bright looking as a more typical 6,700k bulb, even if they put out the same PAR/intensity. Therefore you can get away with it because though it's not appealing on it's own, and seems very dim, it can often complement other bulbs to make your plants look different (and hopefully better).