so as to的so為副詞，後面可以接形容詞、副詞或動詞，as to後面是動詞原形，如：
The building is so tall as to resemble a tower.
He was so angry as not to be able to speak.
such as to的such為形容詞，後面可以接名詞，也可以放在be動詞的後面，as to後面也是動詞原形，如：
His anger was such as not to be able to speak.
The height of the building is such as to resemble a tower.