Hi Sophia and thanks for this second excellent essay!

In your introduction, I really like the first two sentences. The third one, I think, needs to be a little more equal or parallel:

It is, actually, students’ potential and interest that determines what they should learn, rather than the aim to realize equality in number in every subject.

 Alternatives might be:

Our students’ potential and interest should determine their choice of study, rather than a bureaucrat's decision ruling to have equal numbers on every course.

Or perhaps better, because shorter:

Our students’ potential and passion, not some bureaucratic rule, should determine their choice of study. 

Sophia, with your excellent level of writing, you don’t need to rely on stock phrases like “It is widely acknowledged that” and especially, “Scientific research has proved…” What happens if you leave them out? Your essay becomes stronger, not weaker, because you are stating your opinion. It’s an opinion essay, not a research paper: we don’t need to back our opinions up with passives or appeals to authority. 

One tiny point: did you choose to use the word ‘different’ twice deliberately? In that case it could be a style decision, but with only 250 words in IELTS to demonstrate your range of vocabulary perhaps it’s better not to use related words close together.

men and women are different in being good at different tasks.

For example, it would be weak to say

“The company produces many products on its production lines.”

Finally it's worth remembering that many nouns and noun phrases can be replaced with verbs. This can give more life and energy to sentences, particularly long ones.

To conclude, we should keep a clear perspective in mind that attending university is an opportunity for individuals to stretch their potential into full play. 

 

To conclude, we should remember that attending university allows individuals [an opportunity] to develop fully.

I'm not suggesting that the second version is better - with four fewer nouns, it just represents another approach or style decision. Something for your toolbox!