The larger Woodvil is simply called a "Woodvil", it takes an 18650 battery and a 6ml bottle same as a Reo Grand does.
The smaller Woodvil is called "Woodvil 18490" amd takes a 3ml bottle and 18490 battery same as a Reo Mini 2.1.
Often in photos its hard to judge scale and the easiest way to tell a Woodvil apart from a Woodvil 18490 is that the latter has a different fire switch, it is a different style, smaller, flatter at the front, and has a brass surround.
Here's
a good link showing pics of the two models further down on the first page.
For some Reo history, showing pics of the various Reo mods as they were built, have a look at this wonderful thread. Pics of the last run Woodvils start at around page 30 or 31.
http://www.e-cigarette-forum.com/forum/reos-mods/224175-reos-timeline-pictures.html
And another link here too, another wonderful resource:
http://www.e-cigarette-forum.com/fo...escriptions-comparisons-more.html#post7972642
Many thanks to nerak and Rhapsodies Fire for these threads!
ETA - oops, nerak, we posted at the same time!