People with oily skin tend to have large pores all over their face. Their skin tends to be more shiny over the course of the day.
People with dry skin will have no visible pores. Dry skin may appear flaky and sometimes even rough.
People with normal skin may have no visible pores but they don't lean to either side whether it be oily or dry. Honestly, the only people that have truly normal skin as their type are babies and very young children.
Combination skin types have either pores that stops at the middle of the eyes or no pores until the middle of the eye and back to the sides of their face. Combo people are either oily in their T-zone (forehead, nose, and chin) and dry on the outer parts of the fave or dry in the T-zone and oily on the outer parts of the face.