IMR
batteries are a different chemistry.
There are two main advantages:
A) Slower to "flame" when they fail...so safer chemistry. That's why people say only use protected Li-Ion or IMR for example.
B) HIGH-AMPS (High Drain). They put out more amps if you need them.
Disadvantage:
A bit less electricity stored per cubic centimeter of electrolyte. So the actual mAh ratings are lower.
Commonly used for
devices that need the high amps....like booster mods, or mechanical mods where they want a lot of amps (very low ohm stuff) etc.