The 14500 battery is a lithium-ion rechargeable battery intended to be a high capacity replacement for a standard AA battery. The 14500 is physically bigger than the AA, however it can be used interchangeably in compatible devices.
Please reference the battery compatibility within the user manual of your device before making a purchase.
Can my AA device use 14500 batteries?
The voltages between AA and 14500 batteries are not the same. AA batteries have 1.5V while 14500 have 3.6/3.7V. Not all AA devices will be compatible with 14500 batteries because of this voltage difference. Check what batteries your device is compatible with before replacing it with 14500 batteries.