SQL server Express vs developer

Developer Edition supports more features and larger databases. For example, if you want to restore a 88gb database from your production server onto your workstation to do testing, you'll need Developer Edition.

If you're working with Enterprise-only features like partitioning, compression or the Resource Governor. Those features aren't available in Express, but they are available in Developer Edition.

And SQL Express is quite capable of handling fair loads.

SQL Server Express does not require licensing but has a smaller set of features.

Developing against full SQL Server (and Developer Edition matches Enterprise Edition) always leaves the chance that you rely on some feature that is not in the production edition.