What is the difference between 1000mAh and 1400mAh batteries?

Answer 1

280mAh :-) , no really, basically it puts out more power. Some devices can handle the extra power, but others can burn up. You take a chance when you use a higher rated battery than what the device was made for.

Answer 2

The mill-amps pulled per hour by the 1400 battery are 400 mAh higher than the 1000 mAh battery. As the mAh power goes up the longer the electronic device lasts.