Montag, 22, recently slammed Lauren Conrad's line, the Lauren Conrad Collection.
"Lauren's line is not necessarily something I would wear," she told Us Weekly. "She's trying a high-fashion thing, but it's a little overpriced. Mine is fun and flirty for the everyday woman. Most people can't afford $200 for one dress."
"When we were in school, I was the designer, and she was in, like, product development," Montag added.
Click here to compare their designs and here to listen to Montag's new single, "No More."
The Heidiwood event will take place April 11. Contestants must be 21 or older and residents of California. Click here for more information.