Pin to screen will only pin participants for the user choosing to do that and not for everyone in a meeting.
Whereas the Spotlight feature will reflect for everyone in a meeting.
Click on Pin to screen to pin their video during the meeting.

Note:
You can pin up to 5 participants in a meeting.
The pinned users will still be displayed even when a page switch is done in Grid view.
You can pin participants by clicking on the three dots and then selecting Pin to screen.
The participants will be pinned from left to right in Stage view.
The pinned participants will appear below the speaker, arranged from left to right.
Note: Pin video is not supported in Picture-in-picture view.