These are two different SASS syntaxes with the same functionality. SASS was originally the official syntax and it is somewhat different from CSS syntax, with no braces and semicolons. The SCSS syntax is now official and is more like CSS syntax. In practice the choice between the two is a matter of taste. See below an example of the syntax SASS and another one of the syntax SCSS
SASS syntax example:
SCSS Syntax Example:
These codes are actually the same thing only in different syntaxes. Note that using SASS which counts is the indentation, there are no keys or points and commas. Already using SCSS everything is very similar to CSS, you have keys and semicolons. But realize that the SASS features like nesting exist in both syntaxes.