CrashDump file vs Original

Why is the CrashDump file always smaller in size than original one even though seemingly it has everything that original has? What’s the trick here?

Just a guess - perhaps the CrashDump file not include the render or analysis meshes, similar to the file from SaveSmall

The crazy thing is that even it’s the case, when you open SaveSmall’ed file and save it regularly, its size is still smaller than original although by not as much.