Christine — The Jackson one (same size, 7", as the Gulliver example) was made in a 20-rib (or, possibly, 22-rib) dip mould, and I'm now suffering from eye strain! :spls:
The number of ribs, including no ribs, could have been dependant on a variety of factors, including:
Who was making it,What dip moulds were to hand or available,What type of glass was being used, andAny preference expressed by an important trade buyer.
I would go for one or more of these before regarding such differences as indicative of a different manufacturer.
Note that the blue book doesn't list this registration, so it's probably not a glass registration, and may have been intended originally for manufacture in metal and/or pottery/china, although I've never found one.
Bernard C. 8)
... later ... Bonhams example here (http://www.bonhams.com/cgi-bin/public.sh/pubweb/publicSite.r?sContinent=EUR&screen=lotdetailsNoFlash&iSaleItemNo=4162922&iSaleNo=17212&iSaleSectionNo=1), large size again, has 20 or 22 ribs.