The Use of Big and Large

[Big] can describe a concrete size. It also means important or older/ mature.
It is a big dog. / I want to buy a big car and a big house.

He is a big man. / Tonight is going to be a big night for him.

This is my big brother. / You are a big girl now.

[Large] can be used in both concret and abstract size(length and width/ range), and usually describe the quantity (used with quantity words.)
a large room / a large salary / a large geographical area

a large amount / number / quantity / sum of

In addition, large is more formal than big and should be used in writing unless it is in an informal style. It is not usually used to describe people, except to avoid saying "fat."


Reference: Virtual Language Centre / NTNU Web Concordancer