suburbs or outskirts?

[the-good-guy]

Hello
What is the difference between suburbs and outskirts?
In the following senctence you can choose between suburbs and outskirts and outskirts is marked as the right answer:
My uncle and his family have just moved into a new house on the outskirts of the city.
Thank you.
Best regards

 

[Chicken Sandwich]

NOT A TEACHER

"on the outskirts (of something)" is idiomatic. See here. ". . . . a new house on the suburbs of the city" doesn't work.

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[SoothingDave]

A suburb need not be on the outskirts of the city. Some suburbs only have other suburbs as neighbors.

Also, you would be "on" the outskirts, but "in" the suburbs.