Are the open format files that are saved with LibreOffice and OpenOffice act like the OLE files that are saved with MS Office?
Yes and No.
They may transport the same visuals and formats like when they were saved with MS Office, but they may not be 100% compatible at the end.
They are preferable if you are thinking of long term storage or sharing in an open-source-aware ecosystem, but do not share them if you deal with MS-only shops.
For example, I have to endure headhunters that always ask for CV's and resumes in some MS-Word-Format. I prepare and archive such documents in LibreOffice but export and send them as PDF. They never complain.