I don’t know much about thease types of boats. I have seen both terms. What is the difference between a wave ski and a surf ski, or are they just different names for the same thing?
No two different things.
Waveskis are very similar to surf boards that you sit on top and paddle. They are used only for surfing, and are very high performance paddle craft in surf ... as good as it gets ... and pretty hard to learn
If you have a Mac and up to date quick time or PC and quicktime 7.0 you can see some in action here ....
if that does not work look at www.wavemasterusa.com or www.islandwaveskis.com
Surf Skis are very narrow, and fairly long sit on top kayaks or sea canoes made for paddling at high speed off shore in warm waters, they can surf too, but usually for catching off shore swells for extra speed.
See for example ....
(click Valhalla link at the bottom of the page)
DLonborg, Onnopaddle, Sanjay, Scombrid, Iceman etc can fill you in on details.
Surf Ski is generally 19-21 foot long 17"-19" wide and were originally designed for surf rescue, now used mostly for racing. Wave ski is generally 7’-6" to 9 feet long and are used for hi performance kayak surfing.