There are 2 specific kinds of "T5 florescent" lights. There is the standard bulb and fixture that can be used in shops, garages, etc. These have lower power output and come in either 3000k (which is "warm" yellowish light), 5000k (which has a more greenish white light), then there is 6000-6500k bulb (which has more of a blue-ish white light). These you can find in the Lowes/Home depot/home improvement stores.
The other type is the T5HO. This bulb has a significantly higher light energy output and is used more specifically for growing and blooming plants. The bulbs almost exclusively come in either 3000k or 6500k. These 2 light colors are most important for growing most plants. The 6500k being the more "blue" light is ideal for growing plants during their vegetative stage, and can be used for almost any kind of plant.
The 3000k bulb is for flowering plants. If you wanted to grow fruiting plants or vegetables under artificial light and have them produce well, you would want to use a combination of the 2 colors. However for growing and flowering Cannabis, you would use the 6500k light for vegetative growth and then switch to the 3000k bulbs for flowering.
Most of us here are "max yield" growers, so we only use the T5 bulbs for vegging(T5HO with the 6500k bulbs are great for vegging plants) as the flowering bulbs don't produce enough light energy for maximizing the yield potential. They will work for flowering Cannabis if you have only a single small space to work in, but generally Cannabis growers like to use High Intensity Discharge lights for flowering as these put out a lot more light energy, which translates to bigger yields.
Hope this helps. Don't be afraid to ask questions, we all love "talking shop" when it comes to growing Cannabis