It is definitely not just isopropyl alcohol. You can verify this yourself by looking at the MSDS. Whiteboards are non-porous, that's an essential part of how they function. The isopropyl alcohol degrades the non-porous layer on top and over time leads to ghosting.
I think it's sometimes a mix of several alcohols, but that probably has more to do with ethanol being cheaper than with any issue of suitability or effectiveness. Recently, I've also seen "cleaner" that's definitely not alcohol-based and also doesn't work worth a damn.
For questions like these, I would start with the MSDS. While the MSDS doesn't always answer your questions, they tend to be reasonably conservative relative to typical use. For example, they sometimes recommend safety gear that people ignore.
Keep in mind that isopropyl alcohol is available at different concentrations, and the different concentrations have different MSDS. Here are the hazard / precautionary statments from the MSDS:
H335 - May cause respiratory irritation
P261 - Avoid breathing mist, vapors, spray.
P271 - Use only outdoors or in a well-ventilated area.
Note that "avoid breathing mist, vapors, spray" is not an especially strong statement.