What are the main differences between ‘classical’ liberal and neoliberal approaches in the field of IR?

What are the main differences between ‘classical’ liberal and neoliberal approaches in the field of IR?

Structure plan:
-Introduction (200 words)
-Body
-Conclusion (200 words)

This is the structure i recommend using if you have any further points you want to discuss in the body paragraph then let me know. All source must be academic only. Please make sure that the essay itself is 2000 words. Anything exceeding 2000 words should only be the academic sources. Remember to always reference throughout the essay.
1) Title: International relations theory : a new introduction (Author: Jørgensen, Knud Erik, author).
2) Liberalism and international relations theory in Center for International Affairs, Harvard University