I think - not sure - that

* Collabora Online is rebranded, and hosted, LibreOffice Online

* or rather - LibreOffice Online never really existed and it was always Collabora Online Development Edition (I cannot find any LibreOffice Online that's not just Collabora Online Development Edition)

* Collabora Office for Desktop is Collabora Online, packaged as a desktop app

* Collabora Office Classic is just rebranded LibreOffice

* Collabora (the company) is one of the biggest contributors to LibreOffice