Application Development Software

Hi All,
I was going through the tutorial and got confused with Basic Assets Category, Subtype and Association.

This is what my understanding is:-
Cateogory : Something similar to Grouping. We are grouping the Assets here, based on the category name.
Subtype : Subtype is nothing but a Sub class. But how it will be useful i don't know.
Association : Associates, a parent Asset to a child asset. So child asset will get the behavior of the parent Asset. If this is true i can go for the Sub Type i.e. sub class right? Then why should i have to go for Association?

Please let me know the difference.

regards
Sri