With respect to @fandango68, there are a number of misstatements. This part appears correct:
Type 20 - Shamal Ultra, Eurus, Zonda and Neutron Ultra Wheels
Type 40 - Vento, Khamsin and Khamsin CX Wheels
Generic - everything else
I added links to stores that sell the first two types of skewers. I can't find a generic level of Campy skewer. Also, the post may have missed one yet fancier class of Campy skewer for their Bora, Hyperon, or Bullet wheels.
It appears, from browsing Internet catalogs, that the Type 20 skewers and the Hyperon-level ones are an internal cam design, meaning the cam mechanism that closes the skewer is shielded from elements. The 40s appear to be external cam, as corroborated by this post on Velocipede Salon. There are probably some material differences between all the levels of skewers, but I have not physically held any of them. My last pair of Campy skewers is a pair of all steel Record skewers from the 10s era, about the mid 2000s - the nuts, the cam housing, every thing is made of steel. They're heavy but very pretty and functional.
From looking at the catalogs, I would guess that the current high-end Campy skewers probably have some plastic/composite in non-structural places, e.g. the endcaps might have a metal clamping surface surrounded by a plastic nut. I believe this would be true on Shimano's skewers also. I don't know what material Campy's external cam skewers use; I would have to guess that there may be more plastic. This is a guess, I have not personally handled any current-gen Campy skewers.
External cam skewers are usually lighter, but they can get more easily contaminated, and they take more effort to close. More reading at these links. Some prefer internal cam - I'm starting to lean this way.
Last, there is absolutely no reason to
... only use Campagnolo skewers on Campagnolo wheels, as per the above.
Campy skewers will work with anybody's wheels, provided the hubs take quick release skewers. Heck, Campy skewers on Shimano wheels will work, and vice versa (the two companies are long time rivals). Also, I haven't really seen this:
it's ridiculous to think a Campagnolo skewer is also marketed specifically to the number of cogs on your cassette - 9, 10 or 11 speed variations! It's just marketing spin.
Sometimes, when people refer to Campy, they'll state the number of speeds to help readers approximately place the groupset era. Shimano has model numbers (e.g. DA 7700 is early 2000s, 9s Dura Ace), but I don't recall that Campy does this. However, if I said 10s Campy Record (like I did above), you know that this refers to components from the early to late 2000s (roughly).
I suspect that fandango may have seen people say this, but it definitely is not a technical issue. Skewers from any era will physically fit into the OP's wheels if the dropout spacing is correct - since about 8-speed, road bikes have had 130mm dropout spacing, so "8-speed" Campy skewers will work with any road bike that takes QR skewers that's been built since that era. I don't recall that Campy skewers are specifically marketed to work with a particular number of speeds. If their literature implies that, just ignore it, it's BS, and most people who are familiar with bikes know this.