on the side of释义：

拥护…；站在…一边；赞助

例句：

She sat on the side of the bed.

她坐在床边。

by the side of释义：

在...附近；和...在一起比较

例句：

Overlooking the valley the uncle had made himself a bench, by the side of the hut.

老头儿在小屋旁边给自己做了一条长凳，俯瞰着山谷。