grammar - Can present perfect be used instead of present perfect progressive?

I was attending a course lecture about grammar and during a tense review lecture they stated that following sentences have same meaning.

1. Julie has studied French for two years.


2. Julie has been studying French for two years.

I feel the first mean she studied for two years and that is completed now, she is not studying it in present but the second one says she studied for two years and it is still in progress, not stopped.

I want someone to explain if they can be used interchangeably and why is it possible?

Answer

Without other information, neither sentence tells us if Julie is still studying French now.

What both sentences do is to relate the past action 'to study' with the moment of speaking ('now'). Sentence 1 does this with the present perfect. Sentence 2 does this with the present perfect progressive.

Whenever you see a progressive, the idea of duration (roughly represented by ~~~~~~~~) is involved. So, with the present perfect progressive, the past action of studying is seen as a duration that began two years ago and lasts up to the present. Whether or not the duration continues past the moment of speaking cannot be determined by the use of the progressive alone. In fact, we often use the present perfect progressive to refer to a continuous action (an action having duration) that recently stopped. Consider this context: your roommate has just come home. You ask him where he has been, and he says

I've been (outside) running for two hours.

Obviously, your roommate is not still running 'now' or at the moment of speaking. The action of running is over.

Likewise, with your Sentence 2, we would need more context to know if Julie is still studying French now or if she has stopped. The same ambiguity applies to Sentence 1. The basic difference between your two sentences is not whether the action is still going on, but whether the action is seen as a duration. Sentence 1 can be used in a context in which Julie is still studying at the moment of speaking, and it can be used in a context in which Julie is not still studying at the moment of speaking. The present perfect itself does not tell us this, just as the present perfect progressive does not.