I'm confused with proxies, anyone can help me?

I would like to get my feet wet in this IG crazyness ... So I'm looking for a proxy to use my future multiple IG accounts.
From what I know, a proxy is an IP adress that mimic that you "are" a unique device. So I don't understand why there are InstaGram Proxys, Facebook proxies, ABC(specific) proxies. If I buy a proxy it should be mine and I use it for what I want (not IG or FB specifically). What is the difference between a shared proxy, Instagram proxy, private proxy, dedicated proxy?

Thank you

Indeed, if you buy a proxy, you can use it as you want.

However, not many lroxy providers have working proxies for IG or FB and if you buy a proxy and the IP os banned on IG, you can’t really use it.

This is why providers started selling IG proxies or ABC proxies, in this way they provide working IP for a particular platform.

And from a customer point of view, buying IG proxies guarantees your ability to connect your accounts safely to IG, without any banns or additional issues.

Thank you for your answer.
And what is the difference to dedicated and private proxies?

Dedicated proxy IPs are not shared between users, where "private" proxy IPs usually are.