ILL is the older system, where you make the request to the library and they go try to find it.

There’s a newer “Link+” service where you can do the search yourself and request delivery to specific branches. Supported by a lot of member libraries, for example: sfpl.libanswers.com/faq/103121

In our library system, they don’t put Link+ holds with normal holds. You have to go ask someone to look. We get an email that it’s arrived and we have 3 days to pick it up.