The Matte paper printer is used for papers that use Matte Black ink, like Enhanced Matte, Singleweight Matte, Doubleweight Matte and some Fine Art papers.
The Photo paper printer is used for papers that use Photo Black ink, like Glossy, Luster, Semimatte, Semi-gloss and Pearl papers.
Check the instructions that came in your paper box if you are unsure what ink you need to use.