Use both of them for finished and unfinished actions.
Even if we talk about unfinished action using “for” and “since” with Stative verbs (feels, emotions, and possessions), we must use present perfect tense.
•I have known him for years.
•I have three pens.
Note: we have created stative verb exercises series 1 to clear your doubts on the verb. Go through it.
We use “present perfect tense” when we talk about how much or how many –
•I have eaten five pieces of bread this morning.
•She has had three glasses of milk today.
When we use “yet” and “already” in sentences, we usually use present perfect tense with them.
•She has finished her work already.
•Has he arrived yet?
Remember, the present perfect tense is used when an action is over and the result has come from the just finished action.
•I have finished my lunch. Now, I can go out for my tuition.
•I have baked a cake. Would you like to taste it?
In the present perfect continuous tense, the result can come from the action itself even if the action has not finished. The result is often in the form of hear, see, smell, or feel.
•She has been working for hours. She is exhausted. (feel)
•I have been cooking a dish, that’s why the small is all over. (smell)
•I have been talking about a sensitive issue. Nobody is paying attention. (hear)
In the end, we use present perfect continuous tense to emphasise on something that is temporary-
•She has been attending gym these days. (it means earlier she doesn’t)
•I work from home. Recently, I have been working for a company on a project.
Some verbs like live, study, and work can be used as present perfect tense and perfect continuous tense. The meaning will not change.
•I have been living in London for years.
•I have lived in London for years. (meaning same)