Sorry I don't have any exact measurements but ETI says both convert to a double bed so it stands to reason they are very similar in size. That said the 21 dinette should be slightly wider since the trailer is 4" greater in width. I have worked on a 21 in the area of the rear dinette and under the seats and can say that it feels very similar in size to the 19 dinette. Bear in mind that on the 21 you have a full wall on one side (fridge) and the partial kitchen bulkhead on the other. The 19 has a full wall on one side (bathroom) and is fully open on the other. If sitting on the open side on the 19 it may give one the perception of feeling bigger.