yes they are different.
OE tyres are tuned to match the characteristics of the car (in the eyes of the manufacturer).
There can be quite some difference….
In the aftermarket the price may not be any higher, but if you absolutely specify a dedicated tyre (for example the Merc ‘MO’ spec), then the price could be higher as it would not typically be stocked. (unless perhaps you go to the Merc garage for your tyres)