porch, vestibule: a roofed entrance hall built across the front of a large building
This word names the covered entrance hall, or porch, that stood across the front of an important building. It was not a small doorstep but a grand roofed vestibule you passed through on the way to the main rooms inside.
Most often it is the porch of the LORD's temple, the entrance hall in front of the main sanctuary (1 Kings 6:3; 2 Chronicles 3:4). The area just outside that door was a set place for prayer and mourning: priests are pictured weeping "between the porch and the altar" (Joel 2:17), and it is where idolaters stand in Ezekiel 8:16.
In Solomon's palace the same word names several great pillared halls: the Hall of Pillars, and the Hall of the Throne, also called the Hall of Justice, where the king gave judgment (1 Kings 7:6, 7:7). In Ezekiel's vision of a future temple it covers both the temple's own porch and the covered porches of its gateways (Ezekiel 40:8, 40:48).
So the one word covers any of these roofed entrance halls. Which building is meant comes from the surrounding description, not from a change in the word itself.