If it is snowing a lot outside, and you are in your house, and you can't really go outside because the snow is covering your house, we'd say you are snowed under, just like a pile of work covering over you.
如果外面雪下
很大, 你在家里面,因为雪把你的房子都盖住了, 你根本无法出去,我们就会说你被雪压住了, 就像有一大堆工作压在你身上一样。