There seems to be much confusion between the two but it’s really simple so I will try to shed some light on this topic.
A risk is a specific event that may happen. If it does, it will affect your project negatively or positively , so you want to prepare in order to make sure your project goes well.
An issue is something that must be dealt with. A risk, wether identified or not, becomes an issue.
Here are some examples:
Risk: There may be too many users visiting the website, and the server may not handle it.
Issue: Too many users visit the website and the server crashed, we have to add resources.
I hope this helps!