Capacity and capability are not the same

These words often sound synonymous but there is a subtle difference. They directly affect performance or the outcome. Lets see how they can be defined:

• Capacity refers to the ability to do something under standard and controlled conditions. 
• Capability refers to the level of amount of what can be done is normal or daily environment.

E.g. a car has the capacity of seating 5 people, but it has the capability of seating 8 people under extraordinary circumstances. If the car was to transfer 10 persons from point a to point b, its capacity and capability will affect its performance. Whether it is a two door sports car with low capacity or a minivan with higher capacity, the overall performance of transporting the persons will be affected. Even if the cars are same and have equal capacity, a well maintained car will have better capability to timely transport the cargo, thus directly affecting the performance.

Reference
(1). https://www.businessprocessincubator.com/content/ability-capability-capacity-and-competence/
(2). https://www.abyrint.com/capacity-capability-performance/