Adobe Portfolio website has no Category Filter, sorry.
One option is to create multiple project pages in your main site, one each for Illustrative work, Photography, etc... On each project page, add a few examples of your best work along with some descriptive text. Your collection page will contain links to your various project pages.
The other option is to create multiple websites, one for Illustration and another site for Photography, etc... Portfolio allows you to create up to 5 websites.
Hope that helps.
Nancy O'Shea, Product User & Community Expert
Alt-Web Design & Publishing ~ Web : Print : Graphics : Media