Same company, different office, different engine and has been in development for roughly the same time as Crysis.
Not quite.
Far Cry 2 was developed by Ubisoft Montreal.
Previously they have developed Assasins creed,Lost, Tom clansy's rainbow six etc.
They actually also made far cry: instincts for the old xbox in 2005.
Crysis was developed by Crytek, which is based in Germany. They developed the original Far Cry.
Crysis was built on a heavily beefed up Cryengine, which powered Far Cry. Far Cry 2 uses the Dunia engine, which is totally distinct from anything related to Far cry and Crysis.
Ubisoft Montreal have stated that the link between Far Cry and Far Cry 2 is the concept of being lost in an exotic and foreign location. That is upposedly the main theme in both games.