Based on my visits to WonderCon when it was in Anahiem, it is sort of like a smaller Comic Con with fewer attendees. It has a lot of panels and some of the industry exhibitors like DC, Marvel, IDW etc. The only noticeable differences between the 2 conventions are: WC badges don't sell out in a few hours, and the exhibit hall isn't as crowded as Comic Con. Someday, WonderCon will become a 2nd Comic Con owned by SDCCI since WonderCon keeps getting more attendees every year.
WonderCon is owned by SDCCI, actually. Technically speaking, it is basically a smaller version of Comic-Con. Many people refer to it as "Comic-Con's little sister," including SDCCI. Ha ha. ^__^;
According to their "About" page on the website: You are not allowed to view links.
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Login"Comic-Con International took over the show in 2002 [...]."
"WonderCon is literally the sister show to Comic-Con International, embracing all the main aspects of that show, including comics, movies, TV, animation, the Masquerade, and more."