
in my experience: deck wide big and flat and usually in the back made out of wood. usually no cover or there’s only cover over a portion. porch is covered by part of house more narrow and in front. occasionally on the side or in back. patio is outside not elevated like the other two usually paved with stone or gravel.
porches are a covered thing that was built with the house and the roof covers it and it has support for the roof. patios are paved concrete things that can have cover but usually don’t. decks are like a porch but added on usually after the house is built! some have covering some don’t