We use the words, ‘Big’ and ‘Large’ when we talk about size. In modern English, ‘Great’ is not used to refer to size. ‘Big’ is a more conversational word, however, ‘Large’ is a little more formal. Compare the following sentences:
After a large lunch, Hob was very sleepy.
Could I have a big lunch today, my dear?
‘Big’ and ‘Great’ have more abstract meanings. They are often used to refer to important events and actions. ‘Great’ is more format than ‘Big’ in this sense. See the following:
They are making a great or big mistake.
A big or great step forward; a big or great change; a big or great improvement
*** With uncountable words, only ‘Great’ is normally used. The meaning is similar to ‘a lot of’.
I had great difficult in learning Chinese.
Great care; Great importance; Great concentration; Great charm
‘Big’ and ‘Great’ are used simply for emphasis, or to express emotion, either combined with other adjectives or with each other (e.g. great big but not big great).
After a large lunch, Hob was very sleepy.
Could I have a big lunch today, my dear?
‘Big’ and ‘Great’ have more abstract meanings. They are often used to refer to important events and actions. ‘Great’ is more format than ‘Big’ in this sense. See the following:
They are making a great or big mistake.
A big or great step forward; a big or great change; a big or great improvement
*** With uncountable words, only ‘Great’ is normally used. The meaning is similar to ‘a lot of’.
I had great difficult in learning Chinese.
Great care; Great importance; Great concentration; Great charm
‘Big’ and ‘Great’ are used simply for emphasis, or to express emotion, either combined with other adjectives or with each other (e.g. great big but not big great).
