Birthright is a larger scale system designed for interaction between multiple mature countries. The AD&D 2nd Edition campaign setting is set in the world of Aebrynis on the continent of Cerilia which is ~very~ detailed at the ruling level. The setting has divine magical "bloodlines" from the old (dead) gods that allow the regents to rule Law, Guild, Temple, Source and Province/Land Holdings as a core concept. Domain development is done in turns, a turn is a season of three months and the regent gets one Domain Action per month. You can construct some general high level holdings, conduct trade and war, etc. but the building is abstracted into Holdings. E.g. Increasing a Temple Holding from level 1 to 2 in a province may involve upgrading your existing chapel, or building another one in a neighbouring village, or it may just result in more worshippers at existing structures.
A fully 3.5e'd version of Birthright has been created by the community at birthright.net. These rules are meant to be the primary focus of a campaign with "adventurer level" action as a sideline. So much so that there is a Domain Action specifically for it called "Adventure".
Kingmaker is mostly a specific adventure path with some specific rules about carving a new civilization out of largely-unsettled areas and being sustainable. It has a more micro focus - exploration and then construction down to the building level ("I build an inn this turn!") Also keep in mind these are supplemental rules in an AP; there's 9 pages of kingdom building rules, then more later on mass combat and exploration, but the core is small. The rules have been reprinted in Ultimate Campaign, but not in significantly more detail. They are suitable for settlement building as an adjunct to a normal campaign.