Can a semicolon be replaced with "..." (an ellipsis) in a sentence? Is there any difference at all?
An ellipsis indicates either a pause or that something is missing, whereas a semi-colon is used as punctuation to join two clauses. So you would use an ellipsis in a sentence like this:
I went out to buy a ... what is that thing called?
In this case, the ellipsis is indicating a pause while they consider the name of the thing they purchased.
A semi-colon would be used in a sentence like this:
I went out to buy an umbrella; the rain had been falling heavily all morning
The semi-colon indicates that there are two separate (but related) clauses.
No, semicolon cannot be replaced from ellipsis because they have completely different purposes.
Ellipsis is used
In such cases, a semicolon is never used.
It is called "ellipsis" and used to denote absence of parts of sentences. Semicolons are used to connect independent clauses; they separate two parts of a sentence that are closely related.
The ellipsis, as has been mentioned by others, is used to show that something is missing/omitted.
Examples given so far would apply best to spoken English. When written, we might use the ellipsis to abridge a quote:
In his speech, he said "I will do the very best I can... to improve the situation"
where '...' was 'every hour of every day', which does not really add to the meaning so it is omitted.
Also, when referring to a long list:
It is interesting to note the number of pubs in the town that refer to horses: The Horses Head, The Black Horse, The Nags Tail... I'm intrigued by the popularity of this animal in pub names
Where '...' indicates that the list continues.