corridor=porch??

A porch is an exterior appendage to a building, forming a covered approach or vestibule to a doorway.
porch 是門廊,是建築物外部附加的建築,覆蓋著門口或玄關

A corridor is a passage into which several rooms or apartments open.
corridor 是走廊, 是建築物內部通往房間的通道, 可以是密封式(走廊兩邊都是房間)或開放式(只有走廊的一邊才有房間).

照我的理解﹐ 他們其實很不一樣。

porch=陽臺﹐ "騎樓".
e.g. I think my beautiful front porch is really selling the house. (我覺得我漂亮的前門陽臺是我房子的一個很大的賣點。)

corridor = 可以是走廊﹐ 或是通道。 室內或室外都適合用。
e.g. The corridors between forest patches are essential for the survival of large animals in the wild. (森林地域里的通道對於野生的大型動物的生存是必須的)。

e.g. There is a corridor on the top floor that connects the two towers.
(在頂樓有一個把兩座大廈連起來的通道。)