If we are to go too deep…
Language is metaphor.
Slang is a subset of a language.
Jargon is technical slang.
Technical terms are just slang used by the erudite.
Dialect is a way of speaking that may or may not include slang,
Slang is often used by sub-groups to preserve their identity or secrets.
There is no right or wrong way of pronouncing, saying, phrasing or spelling something.
However, agreed norms that are shared by many people make communication less obtuse or prone to confusion.
So two Geordie gas-fitters get along just fine together speaking the broadest dialect, but when they try to communicate with a Cockney they need to both adjust there approach so they have a shared basis of language.
A dictionary tells you [or at least it should] how people spell things - not how they ought to spell things - hence color v. colour etc.
Over time all words’ meanings change - some fall out of use [aka archaic], whilst others become mainstream dictionary entries.
So the back-slang of the 19th c. gutter ‘yobo’ [literally ‘a boy’ said backwards] became ‘yob’ in mainstream 20th c. UK English, with a slightly different meaning of a ne’r-do-well young man, probably with oafish or violent tendencies.
And no one now says someone is a ‘jackanapes’, unless they are in a Shakespeare play!
The word ‘nice’ has had many meanings over the centuries, its current one is not that old…
When a Geordie says he is ‘gannin hyem’ [going home], and it’s likely to be better understood by a German or Dane as it shares some common word use [gang, hjem etc], than a UK Cockney - although he’d understand related words like ‘gangplank’ etc.
Obviously the ubiquity of English world wide makes using some standardized words/phrases, meand you are much more likely to be understood when ‘abroad’.
The variation between US and UK English is also often noticeable [let alone any others like AUS ], but there is a subset not actually spoke by anyone other that some international travelers - like airline pilots - so Airplane v. Aeroplane v. Aircraft etc
So we ought to see that there’s really no right or wrong word or phrase - it depends who you are, where you are, who you are with, and what you are doing…
Attempts to rationalize/simplify English have had limited success.
There is an interesting one, Basic Global English, which seeks to have a limited subset of words/phrasing that will be widely understood…
But of course one of English’s greatest advantages is that it has lots of words that mean the same thing, with subtle nuances, and we adopt foreign words into it quite rapidly, even if we already have some suitable words in use !