Tortuous - twisting and winding, such as driving along a tortuous road.
The wagon was too long to drive along the tortuous track.

Torturous - painful, agonising, upsetting, such as a torturous stay in prison
Listening to the new student play the violin was torturous to the music lover.

To tell them apart, think of the word torture and torturous together as painful and unpleasant.