Can we use the aside tag to create separate columns of content?

Question

I can't really see how this tag is different from the <br> tag......

Answer 1

<br> cannot have childs ( content ), while <aside> is a container ( can have child/content ): this is a drastically difference ^^
And if it isn't much, <br> just break the text stream which continue after, while <aside> interrupt the text stream to flow its content to the stream, before continuing the interrupted stream...

Yes, you can use <aside> to create a separate column of content ( you can't with a <br> ), in semantically meaning that's the content wich is without direct relation with main content. But you need to correctly style it with css to have a visually 'aside column' :P