The maps are maps that come with almost every set. They include a scale, but the scale indicates that Coffer Trap is 50 miles across at one point. In reality its just a few studs...
A special coin comes with any of the three primary sack sets, that supposedly "reveals secrets" on the map.
Four maps were made, for some obscure reason. They do nothing but confuse you, and two of them have sets that don't exist. And another cool feature is the symbols for each faction. A team's symbol is placed next to their biggest set or ship on the map. For example, on the second map the Privateer symbol is next to Mutiny Isle, the privateer skull set which happens to be the privateer's biggest set on the map. (A crying shame, isn't it?)
The first comes with the primary skull sets, and includes the Avenger. The avenger was never a set, dubbing it the least accurate.
The second is the most common, featured in all the 2.0 sets, and the only difference between the first and second is that the second got rid of the Avenger.
The third is the second most common, featuring the Lost Soul symbol, on Plunderer's Port.
The fourth is the most accurate, having all five symbols, all three ships, the canoe sets, and three non-existent sets. See if you can pick them out.
No map has all the sets, for example: all maps leave out Lost Fortune, Fort Defiance, Razorscales, and Crew Collection.