almost the same meaning. 着can be used between the verb phrase. 看着书，走着路，聊着天/正在看书，正在走路，正在聊天

着 = ing， usually in a "when..., ..." structure 他一边吃着饭一遍看电视 He is having a meal while he is watching TV. X他吃着饭。X we never say like that. 他正在吃饭。 ok 正在 , can be simply used as be doing 他正在看电视 He is watching TV. But, sometimes, more often, they are used mixedly, Like: 他正吃着放，电话响了。 When he was having a meal, the telephone rang.

In Chinese we also use 正在 and 着 at the same time. Like “我正在看着电视。” in a real life scenario if we use 着 it means there are other things to say, if there appears only 正在 it means what someone is doing. 着 is closer to a modal particle.

I saw the answer, in a paging web 两个字在特定语态下都表示动作的进行.可是中文也是有词性的.“着”是补语,一般用在动词后,而“在”表示进行状态时一般用在动词前,可以直接跟在主语后,或者省略主语,独立成句. http://www.zybang.com/question/e1a3a376eb3018699c5d55edb74ad4d8.html PD: good question, because I don't think it, It is good question for a native speaker as me too! Fighting