Should and ought to are very similar and can often replace one another in a sentence. They are used to give advice and to talk about obligation and duty. Should is used more often than ought to.
That’s a bad cough. You should/ought to see a doctor.
You should/ought to wear a seat belt when you drive a car.
That should/ought to be him at the door now.
Must can often be used in place of should/ought to but it makes the sentence meaning stronger.
1. ought to
|advice||You ought to drive carefully in bad weather.|
|obligation||You ought to switch off the light when you leave the room.|
|advice||You should drive carefully in bad weather.|
|obligation||You should switch off the light when you leave the room.|