I think 罢了 and 而已 are interchangeable. Meaning 1: Just Example: Chinese:我何尝不想去， 只是没时间罢了。 English: Not that I don't want to go, I just haven't got the time Meaning 2: Only Example: Chinese:我就是一个雇员罢了。 English: I am only an employee. Meaning 3: Don't care;that is all Chinese: 在大街上，人们根本不会仔细看你，只是匆匆路过罢了。 English: On the street, people look not at you but past you. Hope this helps :)

The previous answers give awesome explanations to differences in usage of these two phrases. Ad you can see, they are quite similar. One difference worth noting is that 而已 comes from classical Chinese, so it's more literary or formal, while 罢了 is more colloquial.

Both of them have similar meaning so if I have to differenciate them I would say that: 而己 is to say that something is not a big deal and you can take it easy.. 罢了 is to say that you won´t care what will happen or you just give up something. It also can be use to tell someone that it doesn´t have to be taken so seriously . eg: 我不过开开玩笑罢了 the idea of this sentence is that it is just a joke and you don´t have to take it so seriously... 他不愿意去也就罢了 if he doesn´t want to go, that´s fine, I won´t care!

可以只用罢了和而己。 例： A：你家失火了。There is a fire in your house. B：天哪，我得赶紧回去。Oh my god, I have to run home. A：别紧张，（只不过）开玩笑罢了。Take it easy, just a joke. "只不过。。。而己"翻译为“just ....”

只不过是猫罢了，没有什么可怕的