It sounds like it - and third-party companies will often show you flights that involve different companies on the different legs - which can leave you in a pickle because technically each airline's job is to get you to the end of THIER flight, not the entire journey.
And sometimes with a change of airport!
I remember when in Germany some budget airlines used to say they'd fly to "Frankfurt" (FRA) but actually flew to "Frankfurt-Hahn" (HHN) - 115km away. After arrival in HHN they put you on a bus to FRA that took about 2 hours.