J&L sorts them by category
Power Heads
http://www.jlaquatics.com/category/2...owerheads.html
Wave Makers
http://www.jlaquatics.com/category/100/Wave+Makers.html
A Wave Maker that is not a Power Head controlling device:
http://www.oceansmotions.com/store/i...7caef6e4575cbc
Wave Maker is a very loosely applied term for anything that creates alternating for variable speed flow in a tank. A Carlson Surge Device is another prime example.