Differential Backup of A Table In Sql Server
Consider using Transactional Replication

https://docs.microsoft.com/en-us/sql/relational-databases/replication/transactional/transactional-replication?view=sql-server-ver15

https://docs.microsoft.com/en-us/sql/relational-databases/replication/tutorial-replicating-data-between-continuously-connected-servers?view=sql-server-ver15

It allows keep up-to-date copies of your tables at reporting server, without copying any other tables/data that you do not need