Questions & Answers about Daar is 'n verskil tussen bysiendheid en versiendheid.
What does Daar is mean in this sentence?
Here Daar is means there is. It is the normal Afrikaans way to introduce the existence of something, just like English there is / there are.
So:
Daar is 'n verskil ... = There is a difference ...
A useful extra point: Afrikaans also uses is with plural nouns in this pattern:
Daar is twee verskille = There are two differences
Is daar here a real place word, like English there?
Not in this sentence. Daar can mean a real location, but it can also be a kind of dummy subject in expressions like Daar is ...
Compare:
Die boek is daar. = The book is there.
Here daar is a location.
Daar is 'n probleem. = There is a problem.
Here daar does not mean a place; it just introduces the sentence.
In your sentence, it is the second use.
What is 'n, and how do I pronounce it?