Look at the precision which satoshi used when writing his posts.

https://bitcointalk.org/index.php?action=profile;u=3;sa=showPosts

Punctuation and grammar is sophisticated and exact.

Then look at the letter on this page
http://www.businessinsider.com/dorian-satoshi-letter-and-train-2014-3#ixzz2vCSq2huK

No way, these are by the same person.