How to tell the difference:-

Casual Friends: Never ask for food.
Real Friends: Are the reason you have no food.

Casual Friends: Call your parents Mr and Mrs.
Real Friends: Call your parents mum and dad.

Casual Friends: Have never seen you cry.
Real Friends: Cry with you.

Casual Friends: Borrow your stuff for a few days then give it back.
Real Friends: Keep your stuff for so long that they forget it’s yours.

Casual Friends: Know you.
Real Friends: Could write a book about you.