OK, imagine you are a singer but you're on the keyboard etc. when they say "play" thats kinda like putting the spot light on you. Everybody wants to hear you "solo" the song on the keyboard. Lets say the song is " Amazing Grace", if you've been playing it in the congregation mode then you're probably chording around their singing. Now they want you to "play" meaning make the keyboard sing. Now as spoken earlier this is where you're knowledge of scales, trills, chord embelishment, things you only play when you're practicing by yourself come out. I'll post a video example to demonstrate what I mean........