
James C. answered 10/29/19
18 years web design and development experience; 2 years tutoring
The most important difference for most web developers is use of @import inside stylesheets (NOT HTML pages). You can have one stylesheet "call" or "include" another stylesheet.
However, few people who are learning web development will need to do this. Generally, it is best to use <link> in HTML documents for stylesheets.
@import will force the browser into sequential loading of the stylesheet, so the other stylesheets are NOT loaded concurrently. Very rarely is this desirable.