1. At the part level (.par & .psm), parts can be defeatured to reduce the overhead in a large assembly. This is effectively a simplified configuration. After the part has been "simplified", the part or an assembly in which the part resides can be opened using either the designed or simplified configuration.
2. At the assembly level it is also possible to create simlifications. In my experience this works best with enclosures that contain lots of internal parts that you are not concerned with at a higher level. In the assembly simplification it creates more or less a shrinkwrap around the outside of the enclosure and displays it without the contents.
I don't use either simplification much, even though our assembly model is large, but they are available. Others may be able to speak to specifics of usage. Check Help for simplify in parts and assemblies.
Manager of Engineering - Highwall Miners Caterpillar Global Mining LLC Houston, PA