Size
Sizes pertain to a fashion product’s graduated measurements, such as small (S), medium (M), large (L), and extra-large (XL).
Size ranges pertain to groups of sizes that are related to each other. For example, you can create a size range called "Big Sizes" for the sizes large (L), extra large (XL), and extra extra large (XXL). You create size ranges in the application to organize sizes for a certain theme or classification.
Size categories, on the other hand, are generated to suit different portions of the population, and these provide some variation in proportions in the size sets. Examples of size categories are "Misses," "Juniors," "Petites," "Plus Size," and "Big and Tall."
To develop products in the application, you must define sizes and size ranges and then assign them to the item that you are creating.