A couple of other things that make it interesting/different:
The cover for the cams is slanted, not straight back and forth.
It has an extension bed.
It looks like it might be an open arm.
"internal" bobbin winder (no external tire like the 401 has)
Plus the straight stitch that Candace mentioned.
It also has a different look than the 401, almost like it was the beginning of the Rocketeer phase. Everything is a little more angled, and "spacy" looking. (I have a 401 right beside me at the moment, so comparison is quite easy)