Kevin Hill walks through different topics around high availability and disaster recovery:
Replication—a very Special Snowflake:
SQL SERVER REPLICATION IS NEITHER HA NOR DR.
Not everything in a SQL Server user database CAN be replicated, such as users, or tables with no Primary Key. New objects are not automatically sent from Publisher to Subscriber. System databases are not replicated.
There’s plenty of good information in here, so check it out.