You can share drawing files from AutoCAD and AutoCAD LT, drawing files from previous versions, and drawing files that contain custom objects. In some cases there are limitations.
When you work with drawings created in AutoCAD 2008 (and later releases) in AutoCAD 2007 (and earlier releases), you should be aware of the following visual fidelity issues.
You can save a drawing in a format compatible with previous versions of the product.
AutoCAD LT offers full compatibility when working with AutoCAD drawings. However, you should understand how AutoCAD LT handles AutoCAD-only features.
Custom objects provide additional capabilities to the program and related products. When the application that created the custom object is not available, a proxy object is substituted in its place.