I have yet to meet anyone who has a full and clear understanding of copyright law. One thing I know for certain is that most people (and this includes churches, schools, businesses, and pretty much everyone) take liberties beyond what the law allows. In a church situation, this can be devastating: not only could you face penalties, but you’ve possibly done damage to your witness and credibility.
It’s not comprehensive (since there are other licenses out there), but Christian Copyright Solutions has posted a guide to the differences between the CCLI and the CCS.