Hello Rodrigo! "unfold" means for something to be revealed slowly. For example: "Nobody could predict how the story would unfold". and "develop" means for something to grow into a more advanced, larger, or stronger form. For example: "The fear is that these minor clashes may develop into violent confrontation". I hope that helps!

I can watch a situation unfold, such as a car accident or a news story. This word "unfolds" to me speaks to a circumstance where events are already set in motion and near the climax. I can watch my child develop, I can watch a long TV series develop, I can practice and see my new language skills develop. Develop implies more long term growth or change in a situation. Not a teacher, just my thoughts as a native.