All supositions aside, they are both very lovely examples of Aesthetic Movement period design - heavily influenced by Japanese designs of birds on branches combined with more Western classical border motifs. What caught me off guard even more than the height discrepancy was the difference in materials. The seller hadn't mentioned what the turquoise pot was made from - i assumed it to be earthenware like its counterpart. But no, it is in fact made from Ironstone. This is not the first time I've come across the Powell Bishop & Stonier factory using the same moulds with different raw materials (see a previous blog posting about a jug and bowl set in a Celtic Revival style).
What is most apparent about the two types of ceramic body is that Ironstone, whist heavier and harder, is more suited to intricate moulding as it gives a much crisper result. Take a look at these close ups to see what I mean - the fineness of the moulded design is better achieved in Ironstone than in Earthenware, which tends to give a much softer result. The factory produced a lot of Ironstone wares for the export market - mainly plain wares, or in a simple gilt tea leaf pattern - but they seemed to discontinue with it from the 1880s onwards in favour of earthenware and then finer bone china. The tough ironstone wares were perhaps particularly suited to export as they would've survived the long sea journey more safely than earthenware ceramics.