What is brand hierarchy?

The distinguish between the products of Same demand brand is known as brand hierarchy.For example Apple phone is a brand,but there are different products of Apple phone like Apple SE,Apple iPhone 13,Apple iphone12.For expanding the brand name companies diversify their products by introducing new products.At this time they make a graph chart which is well understood as brand hierarchy.Brand hierarchy is very helpful in modifying the products,introducing new schemes & techniques to bring out something new.