DATA BACKUP from SQL Server Express to SQL Server 2012 Can I restore the backup data from SQL Server Express to SQL Server, both 2012 versions?
Yes. The database format is identical across all editions. An Express Edition database for sure can be restored on a non-Express Edition (you fail to mention whether is a Standard or an Enterprise Edition). The other way around it may be subject to restrictions, Express Edition will refuse to attach or restore a database that:


exceeds the size limitation of Express Edition
contains Enterprise Edition only features, like partitioned tables. On SQL Server 2012 anything from sys.dm_db_persisted_sku_features  will block an Express Edition. This restriction was lifted on SQL Server 2016 SP1.


It is important that both servers (the Express Edition and the non-Express one) be at the same version.