Difficulty levels:
At Chieftain, there are extra happiness bonuses to the human, including 1 extra happiness per luxury. (A bunch of the ones the AI has at all difficulty levels)
Prince and above: AI gets "+1 aggressive" to the listed aggressive ratings in the xml file.
Rainfall: More jungle in wet; less in dry
Temperature: More desert in hot; less in cold
Sea level: More land tiles & less sea tiles in low; Less land tiles & more sea tiles in high
Sparse resources: Even less resources than standard
Continents: On a standard map size this is usually but not always 2. More often than not, you'll need Astronomy to make contact with civs on the other continent. (Or if you suck at science, one of the AIs on the other continent sends a Caraval itself to "discover" your land mass.) Note that it is possible to have a totally isolated start on this map.
Archipelago: On a normal map size, this will either get you your own landmass or one shared with one other AI. (On larger maps you might still find yourself sharing the land mass with 2 AIs.) But unlike Continents, there are routes to make contact with most of the AIs pre Astronomy.
Earth map: (For Battleship Earth achievement) These are NOT scripts and so starting bias does not function. There is only one Natural Wonder on this map (Mt Fuji in the expected location). On normal size (and smaller), the map suffers from it having been designed when cities were allowed to be founded closer together than they are now.
The "+" versions of above maps with Explorers DLC. The most noticeable difference is they attach more small islands and as a side effect relocate most of the city states off the mainland and onto them.
Ring map: Locked to 5 city states, all in islands in the middle; it's often the case you'll need Astronomy to reach them. Note that sometimes the map generator is unable to find five suitable locations for city states, when that is the case, you'll start with even fewer city states. (You pick primary terrain, it's locked to strategic balance) This is nice for players who want contacts with everybody early while only having two borders to defend (it's also clear early on which border you need to defend first)
Large islands: Similar to Archipelago, only your more likely to be the only player on your starting landmass. (But watch out for other AIs wanting to colonize it if you've left a city spot open)
Tiny islands: Even fewer tiles per land mass, in fact normally you hope that the city state did NOT spawn on your starting landmass and that they are instead on the next island over to allow founding a second city before Optics.
Small Continents: On a standard map size, I'd expect to see 3 or 4 Continents. You'll probably need Astronomy to make contact with at least one of the other continents. You'll sometimes have an isolated start, but its more common for there to be another AI or two on your landmass.
Duel map: By default 2 starting player and NO city states. Very few water tiles. You pick the primary terrain. (You can also choose the opponent or as an alternative leave it random) Very suitable for early Domination Victories. Barb camp spawn rate normally much higher than in most maps which a human can take further advantage of by turning raging barbs on to increase barb unit spawn rate.
Great plains region map: In Civ IV, I loved this map type. And in isolation I still do; the problem in Civ V is that the AI loves this terrain as much as I do. This terrain is so good all the AIs will DOW you early and often and so it degrades into a slug-fest.
Donut map: Everybody on one landmass which is an oval; you pick both the primary terrain and the secondary terrain in the middle that's difficult to cross.
At Chieftain, there are extra happiness bonuses to the human, including 1 extra happiness per luxury. (A bunch of the ones the AI has at all difficulty levels)
Prince and above: AI gets "+1 aggressive" to the listed aggressive ratings in the xml file.
Rainfall: More jungle in wet; less in dry
Temperature: More desert in hot; less in cold
Sea level: More land tiles & less sea tiles in low; Less land tiles & more sea tiles in high
Sparse resources: Even less resources than standard
Continents: On a standard map size this is usually but not always 2. More often than not, you'll need Astronomy to make contact with civs on the other continent. (Or if you suck at science, one of the AIs on the other continent sends a Caraval itself to "discover" your land mass.) Note that it is possible to have a totally isolated start on this map.
Archipelago: On a normal map size, this will either get you your own landmass or one shared with one other AI. (On larger maps you might still find yourself sharing the land mass with 2 AIs.) But unlike Continents, there are routes to make contact with most of the AIs pre Astronomy.
Earth map: (For Battleship Earth achievement) These are NOT scripts and so starting bias does not function. There is only one Natural Wonder on this map (Mt Fuji in the expected location). On normal size (and smaller), the map suffers from it having been designed when cities were allowed to be founded closer together than they are now.
The "+" versions of above maps with Explorers DLC. The most noticeable difference is they attach more small islands and as a side effect relocate most of the city states off the mainland and onto them.
Ring map: Locked to 5 city states, all in islands in the middle; it's often the case you'll need Astronomy to reach them. Note that sometimes the map generator is unable to find five suitable locations for city states, when that is the case, you'll start with even fewer city states. (You pick primary terrain, it's locked to strategic balance) This is nice for players who want contacts with everybody early while only having two borders to defend (it's also clear early on which border you need to defend first)
Large islands: Similar to Archipelago, only your more likely to be the only player on your starting landmass. (But watch out for other AIs wanting to colonize it if you've left a city spot open)
Tiny islands: Even fewer tiles per land mass, in fact normally you hope that the city state did NOT spawn on your starting landmass and that they are instead on the next island over to allow founding a second city before Optics.
Small Continents: On a standard map size, I'd expect to see 3 or 4 Continents. You'll probably need Astronomy to make contact with at least one of the other continents. You'll sometimes have an isolated start, but its more common for there to be another AI or two on your landmass.
Duel map: By default 2 starting player and NO city states. Very few water tiles. You pick the primary terrain. (You can also choose the opponent or as an alternative leave it random) Very suitable for early Domination Victories. Barb camp spawn rate normally much higher than in most maps which a human can take further advantage of by turning raging barbs on to increase barb unit spawn rate.
Great plains region map: In Civ IV, I loved this map type. And in isolation I still do; the problem in Civ V is that the AI loves this terrain as much as I do. This terrain is so good all the AIs will DOW you early and often and so it degrades into a slug-fest.
Donut map: Everybody on one landmass which is an oval; you pick both the primary terrain and the secondary terrain in the middle that's difficult to cross.
