两个词都有“认识、识别”的意思，但在具体用法上又有所差别。
1．Realize作为及物动词，可以表达“认识到；了解”的意思。如：
He didn’t realize his mistake until his mother told him.
直到妈妈告诉他，他才认识到自己的错误。
I didn’t realize how late it was. 我没有意识到天已经那么晚了。
She realizes now how hard you worked. 现在她了解你工作得多辛苦。
When he realized what had happened, he was sorry.
当他明白发生了什么事时，他感到很难过。
2．realize还可以表示“实现；完成”的意思。如：
The girl finally realized her dream of becoming an actress.
那个女孩当演员的梦想终于实现了。
3．recognize也可以用作及物动词，表示“认出；辩认；认识”的意思。如：
I recognized his voice. 我认出了他的声音。
I recognized her as my friend’s daughter. 我认出她是我朋友的女儿。
4．recognize还可以表示“清楚知道；认定”的意思。如：
I recognized him to be cleverer than I am. 我认识到他比我聪明。
I recognize that she works harder than I do. 我认识到她比我用功。
5．recognize还可以表示“承认”的意思。如：
I recognize that I have been wrong. 我承认我错了。
They refused to recognize this government. 他们拒不承认这个政府。