Can someone please clarify what the advantages and disadvantages of a LiFe battery and NiMh are?

I have always used NiCd in my model. I installed Chamelion 2200mah AA cells in my original 6EXHP TX and when I obtained a used 9CAP I replaced the measly original but good 600mah with a Hydrimax 1800mah only considering yhat I wanted better life. Both of these are good: neither of my transmitters discharge even if I dont charge them a couple of weeks, note that I fly everyday atleast 30mins on my sim with these

Ameya