I am working on an Office 365 sharepoint online server. and inside the SP admin center . i found an option to Upgrade site collection/s:-
First question. now i am not sure what do Upgrade exactly do ? now when i use to work on SP on-primes, the upgrade is done to the whole farm at once and not to selected site collections..
so does this mean that inside Office 365 i can upgrade certain site collections and leave the other on older versions ?
Second question. is the upgrade similar to running the SharePoint product configuration wizard as in on-premise SP ?
Third question. can I know the current build number for the site collection ? and the build number i will get after the upgrade ?