I have both of these. They appear to be identical except the 'larger' one has a retaining metal rectangle that is normally screwed on to the 4 blade mechanism that can be detached to hold down the larger paper. I've never used it and can't imagine I ever will. Don't make size the issue in this case...buy whichever one is less espensive.
OTOH...consider buying instead a 16x20 or 20x24 easel. As four blade easels are waaaaay too expensive anyway, don't find yourself having to buy a larger one than you currently think you'll ever need someday in the future. It will be quite reassuring to know that you can make any size enlargement you may want or choose to without having to make a second purchase.
edit: the above sounds goofily contradictory. What I mean is that, since there isn't any 14x17 paper made that I know of in this country, that size is unnecessary. Since there IS 16x20 and larger paper available, make THOSE sizes the issue.