I think I've cought the difference. (2) is just incorrect. In this particular situation I should only use the present perfect progressive tense or the first case. But there are few special verbs which allow us to use both tenses. For example, there are live and work words. I can say: "I have been living here for 4 years" or "I have lived here for 4 years". The second sentece means a more permanent state.

Thank you) But I still haven't understood the difference. For example, (1)I have been waiting for 20 minutes and (2)I have waited for 20 minutes. What doest the second sentence mean?

we often use the present perfect simple to say how many - showing a completed action. The continuous can emphasise the duration - particularly for How long? Or that it is a repeated action - I've been learning to play tennis since I was a child. The continuous is more likely for long actions - where the result takes place during the action. Eg. I'm tired because I've been working for 3 hours. It can show an action that has just finished, or may be unfinished. The perfect tense would be complete and would show a result at the end of the action. eg. I'm bleeding because I've just cut my finger. Also for short actions - He's lost his keys. However, both would be used to show that there is an important result now and both show actions which started in the past continuing until now. Sometimes there is a temporary/permanent aspect. I have lived here for 20 years. I've been living here while I finish my studies.

Yes, you are right. As far as I know, present perfect simple is used when you want to describe an action wich has started in the past and has now stopped. On the contrary, present perfect continous is used when you want to describe an action which has started in the past and either is continued in the present or has results/influences there.