In AE, a porch is apparently just about the same structure as a veranda, i.e. an open or enclosed gallery or room attached to the outside of a building.
Besides, a porch (or veranda) can apparently also be designated in some parts of the U.S. alternately as a "(sun) deck", a "gallery", "a "lanai", a "terrace", and a "piazza".
Are any of these regional usages widespread enough to have gotten to flood into mainstream AE?
Also -- in dialectal AE -- can a large outback or outfront balcony, i.e. a platform that projects from the wall of a building and is surrounded by a railing, a balustrade, or a parapet (like of those found attached to hotel suites, or serving as restaurant dining area) be referred to alternately as a "terrace", a "gallery", and a "patio"?