also: キャパシティー
noun
Borrowed from English 'capacity'. Used for physical capacity, mental bandwidth, or the limit of what one can handle. Often appears in phrases like キャパシティを超える (exceed one's capacity) or キャパシティが足りない (not enough capacity).
今週は仕事のキャパシティを超えている。
This week I'm exceeding my work capacity.
この会
The capacity of this venue is 500 people.
能力 means ability or capability, focusing on skill or competence. キャパシティ emphasizes the limit or amount one can handle rather than the skill itself.
Loanword from English 'capacity', adopted into Japanese with katakana spelling.