Billups wasn’t just another school ― it was another world

[keannu]

Does the dash in "[FONT=맑은 고딕]Billups wasn’t just another school ― it was another world" [/FONT][FONT=맑은 고딕]function as an emphasis or paraphrasing?
Does dash always function as emphasis in sentences?[/FONT]

mo3-46
ex) One morning I came across a catalog for a college preparatory school called Billups Academy. It had a summer program and offered scholarships for high school students to ‘deepen and extend their intellectual, aesthetic, and moral interests.’ I applied for and won a scholarship. Billups wasn’t just another school ― it was another world. I was used to big skies, wild water, snakes and horses, and solitude. What waited for me in (d) this new world was tree-lined avenues, brick buildings with white pillars, and a wood-paneled library.

 

[Chicken Sandwich]

NOT A TEACHER

Since Billups wasn't just another school, what follows the dash is a further clarification of what it really was. I would therefore say that it's neither an emphasis or a paraphrase.

 

[keannu]

Can I also use a semicolon or a colon for that kind of further clarification? If there's a fixed rule to choose among dash, semicolon, and colon, it would be quite convenient.

Billups wasn’t just another school (;:―) it was another world.

 

[emsr2d2]

If there's a fixed rule to choose among dash, semicolon, and colon, it would be quite convenient.

Oh, wouldn't that be lovely?! ;-)