The Plus maps use extra scripting for the CS placement. So the CS get clumped and have modestly better terrain for themselves. Great Plains maps have four edges (no wrapping) and for GPP, the CS tend to be more along the edges. The Plus scripts will provide a little more room early, for both the player and AI. The Plus scripts also make an early CS worker steal more difficulty (since the CS are more remote). The fertility of both maps is the same. For some players, more initial space means a better start. Other players really struggle with the Plus script because they depend on the worker steal as well as the early gold and other buffs. Both scripts have the same chances for Salt, the same amount of luxes in total, and the same type and range of luxes. It is not uncommon for any one particular map to not provide every lux and bonus resources. Every map with have all the strategic resources. You will not get CS quests for luxes that are not available on a particular map.