How ozymadian is different from nor …

Both "Ozymandias" and "Not marble, nor gilded monuments" propagate the idea that no man-made structure will endure the test of time. Ozymandias made a splendid city by tyrannizing his subjects and  thought that it will stay there for ever for the world to see and despair. He thought that he would be admired by the world for ever. But when the traveler came upon his statue, it was broken and half buried in the desert sand. All that remained was the pedestal of the statue with his two legs and the arrogant inscription on it and a broken face. Everything else was destroyed in the course of time.

The other sonnet "Not marble, nor gilded monuments" conveys the idea that all the works of man are mortal and subjected to decay as time goes by. They lose their glitter and are destroyed. He compares the life of such monuments with that of literature. While man-made marble structures and monuments suffer devastation, the literature remains untarnished in the mind of generations till the dooms day.