Not quite chalk & cheese but different enough, with the Warco WM-250 being almost twice the price of the Chester 920. On the one hand, there is a veritable wealth of information available on fixing, modifying, improving, and 'tricking out'(as the septics call it)the 9x20 lathe. This model is sold in many guises and you would do well to join the Yahoo 9x20 group to get some information on this. On the whole everyone there who has one realises its limitations but they are generally extremely happy with the lathe, and have as much fun modifying and improving the thing as using it to make stuff. If you are a beginner this size is a good starting point and there is a lot of support out there to help you.
On the other hand the WM-250 is a bit more rigid, offers more capacity at 10"x22", has variable speed and comes complete with a reversible lead-screw for left hand threading and boring backwards. With a bit more capacity coupled with the extra features there *will* come a time when you wish you had this.
I had a play with one of these at Warcos recent open day and was favourably impressed with it. Nice smooth slides with a lovely feel to them, and generally a very good finish. I could compare it directly with my Chester DB10-G which is identical apart from the variable speed and the reversible leadscrew (which the damned thing was sold to me as having but didn't) and the quality on the Warco item was in a different class from the Chester. As you may read elsewhere on here,it eventually went back for a refund.
Chesters customer service was actually very good and I can't fault them at all for the help they provided, but the quality of that particular product was abysmal.