Single Site DR = 1-to-1
Multiple Site DR = 1-to many, many-to 1
Storage Replica (SR): At this time Storage Replica only supports 1-to-1 replications. Between two sites remote replication can be setup bi-directionally, meaning that volume A in site A could be replicated to site B whereas volume B in site B could be replicated to site A at the same time.
Hyper-V Replica (HR): Besides 1-to-1 replications Hyper-V Replica allows for extended (chained) replication. A VM can be replicated from a primary host to a secondary host, and then be replicated from the secondary host to a third host. Please note that it is not possible to replicate from the primary host directly to the second and the third (1-to-many).
Microsoft, S2D [SDS]/2019, Datacenter
Remote Replication Topologies, Disaster Recovery, Data Availability