[dba-SQLServer]SQL Server Dev Without SQL Server?

Does the SQl Server desktop engine exactly duplicate the 
functionality of full-blown SQL Server? I want to develop 
apps for SQL Server backends, but will not have SQL Server 
available during development. I need to be able to design 
databases and write code, then be able to re-create or 
migrate the databases to SQL Server and point my apps at 
the actual database for production. Is this a feasible 
approach, or do I need to find a way to get the full-blown 
SQL Server package to work with?

Thanks for any advice/pointers/information.

Ron Allen