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 it’s impossible to talk silently!
Fact
The only married couple to fly together in space were Jan Davis and Mark Lee, who flew aboard the Endeavor space shuttle from Sept 12-20, 1992 .. More >>