There's a little difference..... i don't believe other users anymore..... i work a lot in youth team development and i've already played a lot of U-20 friendlies...... a lot of times happened that suddenly, when the game is about to start, i realize that my rival team put 1 or 2 players over 20 and CA4 or 5, that makes difficult find serious opponents with real youth teams and players in development..... if i say "let's play U-20 matches", i really mean it, else, i'd say "let's use some youth players, ok?"......
To be honest, set a youth team match having the security that wil be played 100% with youth players is at least interesting.