It is one of the most asked questions What is the difference between restrict vs block on Instagram? So let me give you a short explanation about it.
Both of them helps you to avoid peoples. However, if you block someone, neither you nor the other party cannot message each other and see the profiles, posts, and stories. All the engagements between you will be cancelled.
Though the party will not be notified when you block them, they can find it by checking your profile or commenting or messaging you. They cannot mention or tag you in the future. In simple words, it is an end to your engagement.
When you restrict someone the other party can message, you view your profile, posts, and stories. But you or your followers will not be notified or disturbed by their actions. They can still tag or mention you, and it will be notified to you.
It is a tone-downed version of blocking, where everything seems normal to the other party, but you won’t be disturbed by them. The restricted person will get into a view-only mode. Thus his actions won’t affect you. And he won’t be able to find that you have restricted him.