Both are trace mixes. TMG is Tropica Master Grow - but has lately been renamed to Tropica Plant Nutrition or something like that. I understand its the same as TMG. Don't know what CSM stands for.

TMG is a pre-mixed liquid fertilizor whereas CSM is in the powder form. Many folks use TMG while many use CSM. Seems to me that both have worked well as well as Flourish. I believe Tom prefers TMG over CSM but don't know the reasoning.

I found a link on the APC which has a comparison of the makeup of each fert. The table was put together by Giancarlo Podio. Fertilizer Comparison

Hope this helps.