Why didn't Amr ibn al-'As destroy the pharaonic statues when he conquered Egypt, and does his action differ from the breaking of Buddha statues?

The Pharaonic statues were buried and later unearthed, and the polytheistic temples and images were destroyed. As for the pyramids, they were not worshipped, and their destruction was very costly at that time, unlike the Buddha statues which were recently destroyed when Muslims were able to do so, just as the Prophet, peace and blessings be upon him, destroyed the idols of Mecca and elsewhere.