#Shared Letters in consecutive numbers# Inspired by this puzzling question.

It turns out that, in English, every pair of consecutive integers (e.g. 0,1, 1,2, etc.) shares at least one letter when spelled out (e.g. zErO, OnE (or NOught, ONe); One, twO, etc).

##Input##

Any two positive integers (all natural numbers including 0) up to and including one googol. These can be input as any type you choose, but string representations must only use the characters 0123456789.,' (i.e. the numbers must not already be spelled out on input, but rather input as a numeral).

You can assume that the two numbers will be consecutive.

Some examples of valid inputs:

{1,2}
{"1","2"}
{1},{2}
{{"1"},{2}}
"123,245", "123,246"
"123.456", "123'457"

some examples of invalid inputs

{1,3}
{-1,0}
{1.1,1.2}
{"one","two"}

The Challenge

Given the two inputs, output all shared characters when spelled (both numbers spelled in either lower or upper-case, the same case for both numbers).

A sample implementation for spelling numbers can be found here: https://stackoverflow.com/a/3911982/318414; but I'm sure other options exist; and there are certainly efficiencies to be found given that there are large amounts of shared strings, once you get into the higher numbers. See also https://simple.wikipedia.org/wiki/Names_for_large_numbers for the names of large numbers.

code-golf, usual exclusions apply

Output The shared letters, in any reasonable format. Any of the three numbering systems on the Wikipedia page are valid.

Examples

I will be assuming British English (long form) in my examples.

{6,7} -> "s" or "S" (six, seven)

{999,1000} -> {"n","e"," ","t","h","u","a","d"} (nine hundred and ninety nine, one thousand)

{88955,88956} -> `` (eighty eight thousand nine hundred and fifty five, eighty eight thousand nine hundred and fifty six)

1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000,1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001 -> "ONE THUSADQICL" (ONE THOUSAND QUINDECILLION, ONE THOUSAND QUINDECILLION AND ONE)

9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999, 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 -> el no (nine hundred and ninety nine thousand sexdecillion nine** hundred and ninety nine thousand quindecillion nine hundred and ninety nine thousand quatturodecillion nine hundred and ninety nine thousand tredecillion nine hundred and ninety nine thousand duodecillion nine hundred and ninety nine thousand undecillion nine hundred and ninety nine thousand decillion nine hundred and ninety nine thousand nonillion nine hundred and ninety nine thousand octillion nine hundred and ninety nine thousand septillion nine hundred and ninety nine thousand sextillion nine hundred and ninety nine thousand quintillion nine hundred and ninety nine thousand quadrillion nine hundred and ninety nine thousand trillion nine hundred and ninety nine thousand billion nine hundred and ninety nine thousand million nine hundred and ninety nine thousand nine hundred and ninety nine; one googol)