One way of categorizing Hyperconverged filesystems (or any filesystem really) is by how data is distributed across the nodes, and the method used to track/retrieve that data. The following is based on knowledge of the internals of Nutanix and publicly available information for the other systems.

Metadata

Characteristics

Implemented by

Distributed

Distributed data & metadata

Nutanix

Hash

Random data distribution, hash-lookup (object store)

VSAN

Dedupe

Data stored in HA-Pairs, Lookup by fingerprint

Simplivity

Dedupe

Random data distribution, Lookup by fingerprint

Springpath/Hyperflex

Psuedo Distributed

Data stored in HA pairs, Unified namespace via redirection

NetApp C-Mode

Nutanix uses a fully distributed metadata layer that allows the cluster to decide where to place data depending on the location of the VM accessing it. The data can move around to follow the VM. The Nutanix FS uses a lot of ideas from distributed systems research and implementation, rather than taking a classic filesystems approach and applying it to HCI.