You can create multiple catalogs where each catalog can present items filtered by Main Category (brand) and/or item properties.
You can then assign the catalogs to specific Accounts. If required, you can also assign a price list to each Account per Catalog.
Multiple catalogs are included in the CORPORATE version. If you are using the PROFESSIONAL version you will need to upgrade to CORPORATE in the back office.
This article will explain how to do all of the above: Create Multiple Catalogs.
Using Multiple catalogs is not required, however, the benefits are:
Allowing different Accounts access to see certain items only.
Enables you to create catalogs with different currencies (price lists can have different currencies).
Each catalog can have an expiration date, by which the Accounts need to order by.
Catalogs can have Plans and Target order amounts associated with them.