I was thinking about the similar scenery they make and they both use same installers, are they the same company under different name?

Different companies, but work well with each other.

Qualitywings, FSDT, and Flightbeam all use the same install wrappers, but they are different companies.

FSDT/Cloud9 and Flightbeam uses the same eSellerate DRM/activation system, and so does the Qwings 757 (but not the BAe-146)