Envy is often confused with jealousy, which is the fear of losing what we do have (like a jealous husband who is afraid he will lose his wife and unfairly suspects her to be unfaithful).
Envy, on the other hand, is the inordinate desire to have someone else’s talents, honors, status, abilities, character traits, etc. It can also be the resentment and hatred of someone for having what we cannot or do not have.
Envy can also be a sorrow for other people’s good fortune instead of the Christian response to rejoice with them and for them. The worst form of envy is spiritual, where a person resents the moral improvement of another or becomes angry that someone else is achieving holiness and sanctity in their lives. Bad enough to envy a millionaire for being wealthy, or a movie star for being beautiful, but it is horrible to disdain a saintly person merely because they are improving in the spiritual life. Many of the great saints were envied by their contemporaries.
Wanting to emulate or imitate someone is not envy. However, resenting what someone has or wanting their gifts and talents just for ourselves is real envy. I might be envious of my coworker’s promotion, whether they deserve it or not. I could be envious of the fruits of someone’s hard labor, for example, a neighbor who saved money for many years in order to have a comfortable retirement.
Often, those who did not exercise prudence when they had the opportunity to do so come to envy those who did.