Alkaline
Alkaline AAA batteries are non-rechargeable so once the battery runs down they need to be replaced. They are rated at 1.5 Volts and are commonly used everyday applications such as toys, torches and remote controls. 

NiMh
NiMh (Nickel Metal-Hydride) AAA batteries are rechargeable and are rated at 1.2V. NiMh batteries can be used to replace Alkaline batteries. Can be recharged up to 500 times saving money over standard Alkaline batteries. Excellent for High drain electronic equipment such as Digital cameras, CD players, MP3 players and other Digital equipment.