Watts are part of the electrical properties along with volts and amps. Laptop chargers have the same watts and volts but more amps. 

This is incorrect, Watts (power) is the product of amps * volts. The formula is P = IV. Anything with the same power and voltage will have the same amps.

The volume of power consumed would be Watts * time and gets you to capacity and usage units like watt-hours.