Worship Leader/Lead Worshiper
When I was growing up in church we always had a song leader - someone who would stand in front of the congregation and direct (usually musically trained well enough to actually direct) the singing. Sometimes they would add some wrinkles into the singing, like saying "power" sixteen times instead of two in the line "There is power, power, wonder-working power in the blood (in the blood) of the Lamb (of the Lamb)." Usually they would stand in the pulpit to lead.
As churches adapted to having worship bands, a specific person was the "worship leader" - assuming the same role, just with a band behind him/her instead of piano and organ, with a hand-held mic instead of the pulpit mic. But as worship bands became more common, there came some backlash against the typical worship leader. Some began to think that the worship leader was too visible, that the "worship" was becoming a "show" and instead of glorifying God, it was glorifying gifted singers/musicians (especially the one person who was most visible).
And so we began to see the rise of the "lead worshiper" - check out your praise and worship CDs or this article by Jeff Deyo - the idea is that the only difference between the person in front and the person in the pews is position (and microphone and/or instrument). That what the "lead worshiper" is doing is simply worshiping. certainly not putting on a show. It's all about God, and the congregation is simply invited to worship along with the lead worshiper, who is "really" just worshiping.
The difficulty with this is that some of us need some help worshiping. No, I'm not talking about those who are clap-impaired and don't know which beat is proper to put the hands together. I'm talking about those who don't necessarily realize or recognize that our physical posture actually impacts our spiritual openness. A lead worshiper wouldn't necessarily tell a congregation to "raise holy hands" but would just raise his/her hands in worship. And most in a congregation (who aren't used to raising hands) would never think of raising their hands just because a lead worshiper was doing so. Simply put, a lead worshiper isn't a worship teacher - and that's one thing that most congregations need.
Even at the National Pastors Conference a couple years ago, one of the neatest worship experiences was led by a professor of worship who taught us (pastors) about posture (think about it; are you going to be more open to the Holy Spirit if your arms are crossed against you or if your hands are open in front of you?) about the Temple and the Presence of God, and other things. Though the music "wasn't my favorite style" (an easy excuse not to worship fully), I felt more freed to worship with all of me...
This past Sunday, Chad led worship for us - not just as a lead worshiper (which he has usually been), but by instructing us in worship, how to worship, to give our whole selves in worship. It was fantastic.
That said, (from his standpoint) it wasn't all about him teaching us - he was worshiping with his whole heart and was also teaching us and leading us in worship. Sort of a lead worshiper worship leader.