this is a very interesting topic: the rship of brand &
marketing.
i believe most traditional or academic papers wld tell u that
branding activity is part of the marketing. or in other words,
marketing drives branding.
if i understand correctly, brand equity refers to the
intangible/intrinsic value of the company or product (with the
brand) in the market. for instance, a similar product may be worth
or priced $xx, but due to higher brand equity, it can command ($xx
+ $yy) or in other words, it can fetch a premium price.
as such, brand equity has a lot of influence or relevance in
marketing. The marketing plan's price, promotion or place
(distribution) strategy relies heavily on the brand equity of the
product. For instance, a product with lower brand equity (not so
well known in the market) may require more elaborate planning
&/or spending on A&P activities (pull strategy) to raise
the brand awareness among its target customers.
However, in recent years, a lot of bigger corporations are changing
their mindset when it comes to branding or increasing brand equity.
it has become such that branding drives marketing (not the other
way round).
these corporations are spending a lot more effort and resources to
strategically plan & execute their branding & marketing
activities to reach their brand objective. the brand carries more
than just the intangible value of the product. it also represents
an identity/values of what the company behind the brand stands
for.
Take for instance, VIRGIN. VIRGIN's brand equity is high and they
have been able to diversify their business rather boldly (w/o prior
experience) and some even rather succesfully. No matter what they
do, their working style revolves around being consistant with their
brand value, ie, being "fun, maybe totally irrelevant &
thinking out of the box" style. As such, their target customers
around the world gets a very clear message of what VIRGIN stands
for and even look forward to receiving new products/services from
VIRGIN (partly coz they are curious as to what VIRGIN will come out
with next).
not sure if the above helps. just my personal thoughts on branding
& marketing! 
