Student or Learner
The shop is closed so I can't buy any bread.
The shop is closed therefore I can't buy any bread.
Any difference between ''so'' and ''therefore''?
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
I read on a website that ''so' is informal while ''therefore'' is formal.
The shop is closed; therefore, I can't buy any bread.
Is the comma optional after ''therefore''?
If I don't want use the semicolon then I have to use ''and'' before ''therefore'' as in:
The shop is closed and therefore I can't buy any bread.
Can I also say as in:
The shop is closed. Therefore, I can't buy any bread.
You can say that if you wish. In real life, native speakers wouldn't.
The arrangement is rather formal. I would just say "I couldn't get any bread because the shop was shut".
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.
Of course there are differences between the two words (as Barb-D has clearly pointed out) but they share the same basic meaning in both sentences of 'the result is that'.
Normally, therefore is used to show that a result has been derived logically, so it would be a little out of place in this case. For this reason, I'd say that it is more common in academic English, especially science, mathematics and philosophy (but not really more 'formal'). Consider:
I think; therefore I am.
All men are mortal. Socrates is a man. Therefore, Socrates is mortal.
So if "The shop is closed. Therefore, I can't buy any bread." sounds awkward, it's because, like me, you don't recognise a logical connection between the two clauses -- the result is merely circumstantial.
Of COURSE there is a logical connection.
I wanted to buy bread at that shop. When I got there, the shop was closed. Therefore, I could not buy bread.
Circumstantial would be that the store next door was closed too, or you noticed that the flowers in the shop's window box were starting to bloom.
I suggest it's a matter of "gravitas" that makes "therefore" an unlikely choice for a native speaker. It's not at all of matter of a missing logical connection.