I have been to some 40 countries and have associatied with witnesses in most of them.
There is a remarkably unity in beliefs. I remember once preaching in Kenya with a sudanese brother. He started a sentence and I followed with the next while preaching... Of course as a result of a unified and conformed teaching system.
A specialist on JW (non-witness of course, a scholar) in Scandinavia stated that the JWs are probably the most unified and confirm religious society in the world.
What I did note has ben cultural differences like the following tidbits:
Denmark: brothers are allowed to have beards, even up to giving talks at district conventions.
Sweden: witnesses generally do not dance at weddings.
Germany: beer was served at assembly hall dedication in Munich (been told so)
Italy: sisters should not wear long shirts, even in Italian watchtowers sometimes the photos was altered to confirm with this pracsise (been told so))
Great britain: was told by a sister that she wanted to attend the "labour class" congregation insted of the "posh" one she belonged to. Attended meetings in a cong. where all youngersters were sent to boarding schools.
USA: much more emphasis on submission in marriage etc...
Norway: spanking not allowed since 80s. Governmantal support (repayment of tax money)
Grenada: us witnesses schocked when told this.... "What are parents expected to do then?). Gov sup also hcocking
Grenada: native witness: she used "charismatic" christian expressions and blamed everything on Satan. RArely heard in Scandinavia.
Eastern Europe: very spiritual witnesses, serious believers.
Greece: brother had talk without tie/jacket.