Smaug vs. Thor

The same Smaug who has problem getting through pillars and wooden doors vs the rocket powered dragon who can plough through miles of rock and can outspeeed Mjolnir?
Nope Smaug gets crushed, literally

Crushed? That dragon was literally a tiny tiny fraction the size of Smaug. No, it flees most likely or it would die without effort. One shake of the jaws.