All Omega's..................... are Opel's

All German built,i beleive at Russelsheim and badged as Vauxhall's accordingly
No difference in the two models,only badging! Some European models had different spec levels
but all set ups and basics are the same thing
Check your Vauxhall Omega's VIN plate
Manufacturer:- Opel

I say above i beleive it was Russelsheim,as im not 100% on later cars,but what i do know is that,
All GM 'V' cars were built at Russelsheim
'V' Car was the design name for cars with the fully independent suspension and CIH engines.
All 'V' cars shared the same chassis,floor pan etc
Monza
Senator
Carlton
Royale
Viceroy
Commodore
Probably more that i cant remember...
All these cars were German built and badged according to where they were to be sold....The Royale was built on the same line as the Monza and was the first 'V' car to be badged as a Vauxhall on the line,usually they were badged as Vauxhall's after they had been shipped to Luton
Omega's are 'V' cars because they continue the same suspension,chassis and floor pan set up,obviously with some modifications but basically the same.The only major change was obviously not CIH engines now