[system][docs] Clarifying differences between JSS- and Emotion-based `styled` utilities

Duplicates

• I have searched the existing issues

Related page

https://mui.com/material-ui/migration/v5-style-changes/#styled

Kind of issue

Unclear explanations

Issue description

I was looking for ... and it appears that ...
I was looking into how to create reusable styled components. It appears that there are a couple of places from which I can import the utility fn, but it is not clear which is the correct one (or if all are the same?).

Migration guide says to change any usages of

-import { styled } from '@mui/material/styles';
+import { styled } from '@mui/styles';

But...

• documentation for @mui/styles states that this is a legacy api.
• documentation for styled states to use @mui/material/styles
• tangential documentation uses @mui/material/styles

From the amount of ocurrences, seems like migration docs is outdated. Maybe its the same under the hood? Could anyone shed some light here? Thanks!

Context 🔦

I just migrated a project from v4 to v5.