"Brand wine" is the jargon of wine makers, which means close to and beside famous brands. For example: Wuliangye-Wuliangchun

Jiannanchun-Jiannanchun is not a famous brand wine, which means it doesn't remind you of other famous brands, or it's not very famous. The wine produced by small wineries is called "miscellaneous brand". I don't think you're talking about OEM.