As above, interior is very similar, 200 only has 4 seats though and does have more dash options. 200 chassis is slightly revised, though this is more so on the Cup with the quicker rack from what I have read. Engine is also slightly revised.
If it were me, I would let my budget decide. I think a cheaper 200 would be better value than a more expensive 197, but I wouldn't be too concerned that you were missing out by going for a cheaper 197.