Yes Alphonse,
They are basically the same machine except for bag color. The 4000 has a maroon bag and the 8300 has a dark charcoal gray bag. They may have different style brush rolls, not sure about that though.
The 8300 is kind of rare and hard to find, that's why I wanted one. The 4000's are easier to find even though they are older. I got lucky with my 8300. I got it from a fellow collector who bought it at a Goodwill store for $12.95. The following video was made of my 8300 before I bought it from the collector who made the video.