Abilities and Performance
Abilities are general human capacities related to the performance of tasks. They develop over time through the interaction of heredity and experience, and are long lasting (Desimone et al., 2002).
The main difference between a competency and an ability is that competencies require continuing education opportunities to maintain and they may disappear over time if not used. Abilities may also 'grow' over time, but they are normally relative permanent. Abilities are “fairly stable traits, which in the adult, will not change very much unless the individual is subjected to some unusual environmental change” (Fleishman, 1962).
References
Desimone, R., Werner, J, Harris, D. (2002) Human Resource Development. Fort Worth Texas: Harcourt College Publishers, p. 655, glossary.
Fleishman, E. (1962). The description and prediction of Perceptual-Motor Skill Learning. Training Research and Education by Glaser, R. (editor), University of Pittsburgh Press, p. 138.