The basic difference is that quiet can mean little or no noise, but silent means ZERO noise. If you describe somebody as quiet, it means that person doesn't talk very much. People can also talk quietly (with a very low volume) but itís impossible to talk silently!
Your team must know what is expected of them, and what will make them stand out amongst others. Each member of the team must be given clear measurable goals. Discuss and agree with each member before making it formal, your team member must accept it whole heartedly otherwise it won't serve any purpose.