OneDrive App needs "Export" and "Open with" features, found in Dropbox App which let us open or attach real file on any chosen App.
Dropbox Android App lets us attach real file from Cloud to any App using EXPORT feature in the menu. I.e. You can attach real file in Gmail draft with one click on EXPORT, while OneDrive has to save file on local drive first. Onedrive cannot Export epub file to Play Book. That is because the Share function only share Link, not real file. So you cannot open your file with the App you want unless you download onto the local drive.
"Open With" allows you to ope file in any App you choose such as and it can save back to Dropbox. For OneDrive, you have to save real file on local drive, edit and upload it back to the same location. Onedrive needs these same features.