Do you believe Satoshi was a pseudonym used by more than one person that's why there's differences in written English ?
Opsec.
There's a third option: he doesn't know and didn't care how to write the words. I'm neither British nor American, but was taught British English on school. Most of the internet uses American English. I couldn't care less I type "optimised" or "optimized", and I'm pretty sure I've used different spellings for the same word once in a while too. I see no reason to assume Satoshi would use perfect English without mistakes.
Or all 3 options could be valid at the same time.
Also if Satoshi was using different computers in different locations with different browsers etc.
there could have been spell checkers used or not. Lets face it whomever the person or group
was the great art was to create and remain anonymous.
Here is an article which is very interesting and pretty much conclude that satoshi was
different people, Its very technical, I found it difficult to read parts.
https://towardsdatascience.com/stylometric-analysis-satoshi-nakamoto-294926cdf995Some extracts below.
Abstract:
Natural Language Processing tools were applied to the Satoshi Nakamoto’s Bitcoin paper to compare it to numerous cryptocurrency-related papers in an attempt to identify the true identity of the unknown Satoshi Nakamoto.
There are two parts to the paper; the first part is stylometric analysis on the linguistic features generated and n-grams of each document in the corpus consisting of the relevant literature listed on Satoshi Nakamoto Institute and using machine learning models of the linguistic features to predict an author/authors on the Satoshi Nakamoto’s Bitcoin paper and his personal email texts.
The second part is semantic similarity analysis where the content of each document in the corpus is compared in terms of semantic similarity number using the built-in functions in spaCy and gensim. The results from the two parts suggested which author/authors in the corpus are linguistically and semantically similar to Satoshi Nakamoto.
4 Results
According to the classification algorithms in Table 3, they all predicted that Nick Szabo is linguistically similar to Satoshi who had written the Bitcoin paper and Ian Grigg is linguistically similar to Satoshi who had exchanged the emails.
5 Conclusion
Based on the results, Satoshi who had written the Bitcoin paper may not be the same Satoshi who had exchanged emails. Satoshi Nakamoto may possibly be more than one person; Satoshi Nakamoto is a pseudonym for a team of computer scientists and cryptographers who were involved in creating Bitcoin and blockchain.
Nick Szabo and Ian Grigg are the two authors who are linguistically similar to Satoshi Nakamoto in the Bitcoin paper and his email texts, respectively. In addition, Wei Dai and Timothy C. May are two potential candidates for the Bitcoin paper in terms of semantic similarity.