Actually we cover this very topic in our training classes, but the short version is that the express version is the same as the standard with the following limitations:SQL Express Limitations
- Only supports database sizes up to 4 GB
- Only uses a single processor core (or thread if using hyperthreading)
- Only uses up to 1 GB of RAM
Past that, they are the same. In our medical application, we have many users that stick with the express version for smaller shops until they get close to the limit then purchase a full version of SQL. When this is done, it is just a matter of loading the full version and moving over the database if the instance changes.
During development, we generally stick with the full version. We use the Developer Edition for development usually, but also have a Standard Edition or two loaded as well.