I’m having difficulty searching for the answer to this question since {} and [] don’t seem to affect search queries. My question is simple: how are these syntaxes different in meaning?
{short_code}{/short_code}
[short_code][/short_code]
shortcodes between square and curly brackets
To WordPress, as it parses through the content, only the tags using square brackets will be treated as short codes.
The curly bracket example given would not be parsed by the WordPress core. It is possible the tag would be parsed by a plugin or theme if they are looking for hooks in the content that they don’t want handled by the core functions for some reason.