PHP API OnlineRequest vs Request

I’m using the Words PHP API and I’ve noticed each API request class comes in two flavours; an ‘OnlineRequest’ and just a ‘Request’, e.g:

Class BuildReportOnlineRequest {...}
Class BuildReportRequest {...}

Class InsertHeaderFooterOnlineRequest {...}
Class InsertHeaderFooterRequest {...}

I can’t seem to find an explanation in the documentation - which Classes should I use and why?

@FFSPUD

Please note that the online API requests do not require the use of cloud storage. Whereas, other API requests process the documents from cloud storage.