A logo is one element but the brand isn't just about a logo, it's about the whole being greater than the sum of it's parts and therefore about a whole visual language.
A language that is subliminally read but none-the-less there.

The simplest example of one brand element is the use of colour. To a company involved in finance, red can mean danger, however, if you're a ladies lingerie manufacturer it can symbolise love, sexuality and femininity. Just a colour on it's own speaks a language, let alone how that colour is used, where it's used, what font's are used, sizes of font and brand imagery which are just a few key elements that combine to form a brand image. Get it wrong and everything that is created after it, from brochures to websites will also be wrong. Get it right and everything else will fit into place nicely.