Lululemon Athletica claims in its lawsuit filed in the U.S. District Court for the Central District of California that Costco has “unlawfully traded” on its reputation, goodwill and sweat equity by selling unauthorized and unlicensed apparel that uses knockoff, infringing versions of its patents.

Lululemon Athletica has filed a lawsuit against Costco Wholesale, alleging that the warehouse-club chain is selling knockoff versions of its popular activewear through its Kirkland private-label brand.

People on social media and news outlets have noted that Costco sells items similar to pricey Lululemon apparel — but are they too similar?