How so I keep from confusing Tunbridge ware and Sorrento ware?

Dear 1018, 

You keep confusing between them because they are quiet similar, and it
probably takes an expert to tell them apart.

A site specialising in antiques, writes about the Tunbridge ware: 
"The timbers used, unlike Italian Sorrento ware, were in their natural
colour, although sometimes this colour was enhanced with chemical
processes."
(SOURCE: Antique Boxes in English Society, by Antigone 
<http://www.users.globalnet.co.uk/~boxes/boxweb/material.htm>).

The Antique explorer concurs:
"Only naturally coloured woods were used in contrast to the dyed
wooden Sorrento ware and German strapwork that are sometimes mistaken
for Tunbridge ware"
(SOURCE: "APRIL 2003 ISSUE",
<http://www.antiquexplorer.com/Antiques/APRIL03.pdf> PDF document -
requires Adobe Acrobat).

There is no further difference, unless you count the price... 

I hope this answered your question. My successful search was
[Tunbridge Sorrento ware unlike]
<://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&q=Tunbridge+Sorrento+ware+unlike>
but naturally I also searched further with other terms that might
explain the difference.

Please contact me if you need any further clarification on this answer
before you rate it.

I did receive an amazing amount of material. I should have also asked
for differences in values between the three types of wood inlay
products (from Ialy, Germany and England). It was my fault for not
asking. I thank the researcher for all the effort.