Diferenece between 2 step format in Solidworks
If you want to save a model in step format, you have 2 choose in Solidworks,
what's the difference between them?
The wikipedia link from @Sudhir_Gill above explains all STEP formats comprehensively.
Basically either format you chose should work fine; the standard has assigned STEP 203 as "General Mechanical Design" format and STEP 214 for "Automotive Mechanical Design"
Also see: http://www.mcadcentral.com/proe/forum/forum_posts.asp?TID=32703&PN=16
STEP consists of various Application Protocolls (APs) of which AP 203 and 214 are commonly used in mechanical engineering. There are a lot more of them out there, but only few are actually in use. STEP acts as a container for specific types of information, just like PDF works for images, texts and in fact 3D models too. For example AP 242 (I think) is being designed for systems engineering applications and there are a few others that are fitted to electronical CAD (ECAD) or different types of simulation data.
In short: I don't know the specific capacities of these two, but if you don't know either and nobody asks specifically for AP 214, just use AP 203.