Qual è la differenza tra こい 恋 e あい 愛 ?Sentiti libero di rispondere con un esempio.

It is very difficult. Even in Japanese lol.
I found a thread where Japanese talk about 恋 and 愛.
(https://okwave.jp/qa/q2391685.html)

Answer 1)
Love has 2 stages. The first stage is that you fancy/like someone and want to go out with this person. That is "Koi".
The second stage is that as you go out with this person and get to know him/her more, your loving feeling towards him/her increases. This is "Ai".

Answer 2)
The Japanese word "ai" means to keep thinking of someone and try to take the person into your consideration.
The Japanese word "koi" is to want yourself to be loved by someone.

In my opinion, 恋 is used when referring to undeveloped love and 愛 is used when referring to mature love.