Chocolate liquor (called cocoa mass in Europe) is ground cocoa beans, which themselves consist of almost equal amounts of cocoa butter and dry cocoa solids (there is no alcohol in chocolate liquor).
A little extra cocoa butter is added in the production of most chocolate and some companies may add a little extra cocoa powder. Cacao content, expressed as a percentage, indicates the total ingredients in the chocolate that are derived from the cocoa bean, including chocolate liquor and any added cocoa butter or dry cocoa solids. Therefore, cacao content may be a few percentage points, or as much as 8%, higher than the % of chocolate liquor.