Everything I read looked like local file storage solutions. I didn't see anything that jumped out at me as network storage like backing up to Amazon or to another generic server somewhere.
For example, NFS/SMB are file based network storage. Amazon is a cloud provider, that offers storage in various forms, but I guess, you mean the object store S3.
Besides the naming differences, a low bandwidth and high latency storage (in most cases) is not suitable for the vzdump backup. Vzdump is writing one big file. That is always a full backup.