In Assembly Environment there are two options insert component or product so, what does it actually mean?
It means that you can assable products in yout product. Some times it is easier to assamble some parts to a product, and import them as a product in your general product.
So you can reduce your number of constrains, etc
Component does not have file i.e. we can add the parts into components and by copying we can use number of times within a CATProduct, without generating lots of file.