SLA Models

STL (.stl) format is the industry standard for rapid prototyping, but VRML is also supported by some rapid prototyping systems. VRML provides the ability to include color information with the 3-D file, while STL does not. For this reason, VRML is popular for rapid prototype systems that support multiple colors. SLA (Stereo Lithography) does not support multiple colors, so there is no particular reason to use VRML instead of STL.
Ignoring characteristics of the specific rapid prototype system used, the quality of the resulting SLA model is primarily related to the quality of the STL or VRML created from SolidWorks, Pro/E, or the tool of your choice. Within SolidWorks, there are multiple options and settings for creating STL files. The proper settings will result in very nice SLA models while in appropriate settings can cause unexpected results. Since I normally don't use VRML, I'm not familiar with the VRML output settings.

Our SLA vendor does not accept home-spun STL fies. Too many problems with customers complaining about the quality of the models resulting from poor resolution (caused by said customers).
Our vendor takes neutral files and makes their own STL's with very high resolution. No more complaints.

When you save your part to a *.stl click on the Options button for control over the output resolution.

Thanks to all of you. You have been very helpful with your explanations.