When you say 代理店, there are many types of 代理店, for example, 販売代理店 meaning sales distributor, 取次（とりつぎ）代理店 - agent, jobber, 生命 / 海上火災保険代理店 – life insurance / fire & marine Insurance agency / agent, and notably 広告代理店, ad agency known by "Mad Men."
Even Dentsu, the world's largest ad agency that handles more than ￥4,642 billion (US$43.6 billion) ad expenditures a year (2015), dictates, and virtually monopolizes whole the Olympic Games-related business in Japan is simply calld a 代理店 in ad world, because their business is essentialily a broker of time and space between mass media and advertisers.
代理店 is also called as 取次（とりつぎ）店 and 中継（なかつぎ）店.
We even call a wholesaler as 一次卸代理店 (primary wholeseller) or 二次卸代理店 (secondary wholeseller). When you say 販売代理店, it can be a retailer who sells the products of a particular maker. So the scope of the functions and meaning of 代理店 are very broad.
“Authorized dealer” can be translated as 特約販売代理店. Electric /electronic products makers such as Toshiba, Hitachi, Mitsubishi and Sharp used to organize their sales channels under the umbrella of this name until a couple of decades ago, but this system is almost extinct today along with the rise of large scale electric / electronic products distributors like Big Camera, Yamada-Denki, and Yodobashi Camera.