Egyptian architecture focused heavily on the idea of permanence, particularly tomb architecture. The scale of tomb architecture was very large and the material of choice was stone. Furniture was often made of wood and didn't have the same permanent quality. Egyptian art was stylized and maintained a great deal of consistency throughout the centuries.
Grecian architecture was all about achieving perfection. Buildings were proportioned according to the proportions of their parts, such as columns. Grecian art was more life-like than Egyptian art, focusing not so much on symbolism but on perfection, beauty, and the "ideal."
Roman architecture was grander in scale than Grecian architecture. Much Grecian influence was present in Roman architecture, but decor became more prominent and opulent.