Q. Do all Azure VMs with the same network bandwidth in the VM sizing document have the actual same bandwidth limit?

A. No. The document at https://docs.microsoft.com/en-us/azure/virtual-machines/virtual-machines-windows-sizes documents the network bandwidth for VMs which ranges from low all the way through to extremely high with medium, high and very high in-between but this does not mean there are only 5 different bandwidth speeds for VMs. Instead VMs in the same category of bandwidth will vary based on their size with the larger VMs in the category being towards the high end of the limit for the bandwidth category. There is no documented exact number and they may even vary between regions as new features are deployed. If you require a certain bandwidth I advise running a test between VMs to see if it meets requirements.