Design capacity
The design capacity of a battery indicates the maximum amount of energy the battery can store when new. It is a fixed value typically expressed in units such as milliwatt hours (mWh) or milliamp hours (mAh). Physical characteristics such as the number of cells, size of the components, and spatial constraints are all factors in determining the design capacity of a battery pack. For example, large form factor “desktop replacement” notebooks can accommodate bigger battery packs with a higher design capacity. By contrast, an ultra-portable form factor must be thin and light. Therefore, such designs are restricted to smaller, lighter, battery packs with a lower design capacity.
Full charge capacity
Although design capacity communicates the maximum energy level a battery can store, full charge capacity is more apparent to the end user. Full charge capacity is the amount of energy the battery can store when the state of charge is 100%. When a battery is new and unused, the full charge capacity value equal to the design capacity value. Occasionally, a new battery may report a full charge capacity which is greater than the design capacity value. In these cases, the battery may require a few charge cycles for the OS to report the correct values. However, in all cases, design capacity is a static value that does not change, full charge capacity decreases over time as the damage to the battery accumulates.
after 2 years it’s still at 100%?! 
