Today, ProShares launched the ProShares Online Retail ETF (ONLN). According to the prospectus for the fund, ProShares claims that ONLN is "the first ETF focused exclusively on retailers that principally sell online."Astute investors know that this title already belongs to the Amplify Online Retail ETF (IBUY), which has accumulated about a half billion dollars in assets. According to Simeon Hyman, ProShares' global investment strategies, “the key distinction is we’re retail exclusive, while IBUY has some travel-related companies which we really don’t consider to be retail." It's a minor distinction between the two, but the claim of being the "first" such ETF in the space is misleading.A look at the fund's top holdings show that Amazon (AMZN) and Alibaba (BABA) make up around 40% of the fund.By comparison, Amazon and Alibaba account for less than 5% of IBUY.Among other differences, IBUY has about 20% of assets invested overseas, with allocations to the U.K., China, Japan and Germany. ONLN has 25% invested abroad, with most of it going to China. IBUY has about 30% of assets in large-caps, while ONLN boasts that it "focuses on the largest players in the space". ONLN's expense ratio of 0.58% comes in just a bit below the 0.65% expense ratio of IBUY.ONLN will fit in nicely with ProShares' other retail-focused ETFs - the Decline of the Retail Store ETF (EMTY) and the Long Online/Short Stores ETF (CLIX).