If one is a senior translator, he may have his own customers, and can find new customers from the internet, then he's called a self-employed, and maybe he can ask other translators to help him when there's too much work to do.
If one is a junior translator, he may have to emploed in more than one translation companies, and he does his work at home, and his work is given by these companies, although only when the companies need translation work, will they give him the work to do, I guess he can be called a freelance.
Just a shoot in the dark.
![Stick out tongue [:P]](/emoticons/emotion-4.gif)