[dralley]

Profiles and containers solve two different problems. Multiple profiles will keep websites that you only log into from one profile from leaving cookies that can be seen by the other profile, but containers prevent one website from leaving cookies that can be seen by any other website even on the same profile, and prevent that website from seeing any cookies other than their own.

[dredmorbius]

AFAIU containers can be and are shared by multiple domains, though domains pinned to exclusive containers won't be visible to one another.

Opening a domain in a container, then other linked sites from that page, generally remains within the same containdr.

[iamdamian]

According to this thread, they largely solve the same problem:

https://news.ycombinator.com/item?id=20258432