Tell: To a new team member, he lacks the knowledge and have a good will to do thing, we just tell/order them to do.
Sell: To a junior team member, he still lacks the knowledge and has low will to do thing, we need to teach him to do things.
Coach: To a senior team member, he has the knowledge and has low will to do thing with a poor result, we need to coach him to do things.
Delegate: To a mature team member, he has both the knowledge and will to do things, we delegate the things to him letting him accumulating experiences.