One difference that came to my attention last week is that using physical phones and the original 3CX Phone for Windows registers with 3CX using an IP address while the web and Electron clients do not.
That may seem both obvious and trivial, however, we use the registered IP address to identify the location of the phone so we can update their emergency group membership. IP based registration is only possible with physical phones and the original 3CX Phone for Windows. That may be a consideration when deciding which client to roll out within your organization.