és vs. meg?
It's my understanding that both és and meg mean "and". But I remember someone once asked if, for a certain sentence, their translation would work (including both a different word order and replacing és with meg), and the response they got was essentially "it's technically correct but doesn't sound educated." Is meg actually interchangeable with és, or does it mean "and" in the same way that pedig does? (i.e. not really "and"... more like "but" or "whereas") Is that why it sounds uneducated, or is it because of some cultural technicality?
If they connect single words/phrases, és and meg are interchangeable.
"Vettem almát, körtét és barackot." = "Vettem almát, körtét meg barackot." ("I bought apples, pears and peaches.")
You should use és in more formal settings, but in colloquial speech you wouldn't come off as uneducated if you used meg.
When connecting clauses, meg is synonymous with pedig instead.
"Én elmentem a boltba, te pedig otthon maradtál" = "Én elmentem a boltba, te meg otthon maradtál." ("I went to the shop, whereas you stayed at home.")
The rule is similar, use pedig in formal settings; both are fine in colloquial speech.
What's important to note is that in such sentences both meg and pedig have to be in the second position of the clause, directly after the word/phrase they refer to. If pedig is in the first position, it means "although" / "even though" (and meg can't substitute it).
"Nem köszöntem neki, pedig ismerem." -- "I didn't greet him, even though I know him."
On top of this great explanation, "meg" also means "plus" in calculations. "Kettő meg kettő" - "two plus two", not really interchangeable with "és". But this connotation may carry over with "meg" into its "and" role, in trace amounts.
Also, physically, or physiologically (?), "meg" is a shorter, faster word to say. It rolls out easier in many situations. I guess it's a rhythm and harmony thing. So, "meg" is very much in use, quite interchangeably.
Then there is the coincidental (?) match of "meg" with the preverb "meg-". So, don't get fooled. If you see a "meg" in an unusual place for an "and", it is probably the preverb, separated from its verb. A preverb can even stand for a whole sentence. But that's a whole other topic.