Both are owned by the same company, but perhaps the manufacturing plants are different.
As an aside, Sunseeker and Forester are identical except for the Forester sometimes comes with slightly upgraded offerings standard. Think Ford vs Mercury back in the day.
Coachman verses Sunseeker would be more like Chevy verses Buick. Same manufacturer with several shared components but some different designs.
You may want to check out Winnebago/Itasca, Nexus and Fleetwood as well for reference.
History: '08 View, '05 Chinook, '01 Jamboree 24D, '78 Apache Popup, 81 Komfort Tlr,
84 Mazda B2000 'w canopy,
Tent from wedding shower in '96