Abilities usually refer to things someone is naturally good at. But may have been improved by training. Example: Someone who is excellent at running/sprinting. Or a vocalist/singer Associated with "talent" Skills are acquired or learned. Skill and ability are often used interchangeably. It is assumed that if someone has the ability or skill to do a job they are competent. Competence is how well or effectively someone can accomplish a task. Example: Three people are given the task to enter data into a spreadsheet. One is able to quickly enter the data with very few errors. The second can enter the data very quickly but has many errors. The third formatted the data nicely, but did not enter the data in a timely manner. I would say that the first person is the most competent of the three people.