Yes they're different. A FW is a low shank machine and the 301 is a slant shank machine. The bobbins/bobbin cases interchange but the feet do not. As for the walking foot, just be aware that there was never a walking foot made for a 301. The slant walking foot sold for the 301 has been modified so it fits, but the legs on the foot do not match the feed dogs on the machine(like a walking foot is supposed to fit) so it works okay for some people and doesn't for others.
Cari