People tend to think that Egyptian building styles stayed the same for the whole period of Egyptian history, from the beginning of the Old Kingdom to the end of the New Kingdom two thousand years later, but that's not true. The Egyptians built different kinds of buildings at different times, just like any other group of people.
In the early part of the Old Kingdom, the Egyptians built mainly mastabas, a kind of tomb with a flat roof like a house. Then throughout most of the Old Kingdom, the Egyptians built the pyramid tombs which are now so famous. Of course they also built smaller buildings like houses and butcher shops.
In the Middle Kingdom, the mastaba tomb came back again, although in a more elaborate form for the Pharaohs. They didn't build any more pyramids.
New Kingdom temple of Amon at Luxor
Then in the New Kingdom there was a lot of building that was not tombs: temples for the gods especially, but also palaces for the Pharaohs. You could compare these New Kingdom temples, with their columns mainly on the inside of the walls, to buildings from Shang Dynasty China, about the same time, where the columns are around the outside.
To find out more about Egyptian architecture, check out these books from Amazon or at your library:
Make This Egyptian Temple (Usborne Cut-Out Models), by Iain Ashman (1999)
Pyramid, by David Macaulay (1982).
The Art and Architecture of Ancient Egypt (Yale University Press Pelican History of Art), by William Stevenson Smith and William Kelly Simpson (revised edition 1999). The standard for college courses.