Question

Do oxygen and nitrogen vary from place to place

Answer 1

Yes it's true.

You will be able to understand it by burning candle in the absence of air , you will be failed to burn it. Because air contains some matter that support combustion. It's an Oxygen.

And when you blow over a burning candle it will be extinguishes, that means it contains in combustible gases that do not support combustion. It's because of the presence of Nitrogen.

Hope it's useful.

All the best.