At Spinoza's blog there was a discussion regarding the pantheist position and the centuries-old criticism that pantheism is nothing but atheism in ill-fitting religious clothing. If you are equating the universe with God, why can't you just drop the God term entirely? Do we really need another synonym, especially one that carries such heavy connotations?
But I think that the pantheist position is a far cry from atheism. Granted, to the theist who insists on anthropomorphizing God they are equally heretical, but they are actually only superficially similar.
The major difference lies in the appreciation for existence. What is existence really? Is it some random backdrop in which we find ourselves or is it an integral part of who and what we are?
Pantheists are generally philosophical Monists, everything is 'one thing' and all comes from the same source. All things within the universe are interconnected.
Pantheists may also believe that there is value external to human judgement for things like morals and aesthetics. That these are not human constructions but that they are human fulfillments and recognitions of aspects of reality. The typical atheist position which undermines such things as epiphenomenal are actually integral (as are all things) to the pantheist position.
The Pantheist may understand a certain way that things ought to be, as opposed to the atheist which sees such ideas to be a matter of mere personal preference or irrelevant.
Atheists don't tend to make metaphysical assertions, they just harp on the failures of theism. If they follow scientific skepticism then their metaphysical views may be nothing but basic materialism.
The ultimate difference lies in what each side considers the basic substance of the universe to be like. The atheist conceives of nothing but subatomic particles whizzing about or random quantum fluctuations while the pantheist imagines a fundamental well-structured ground of being.
Personally, I don't know if I'd call myself a pantheist. Perhaps I'm more of a panentheist wherein physical existence is a manifestation of a higher existence, albeit a still integral one. The question is then what we mean when we use the term 'universe.' If it means just physical reality, then I'm a panentheist. If it means all things then I'd have to a pantheist.
Pantheism is a positive belief that the universe holds properties worthy of reverence for its own sake and that are truly integral for a meaningful existence. To refer to such ideas as simply the physical universe loses a lot of the intended meaning. The term 'God' as ultimate existence is not just a semantic ruse, it is truly a more apt expression of pantheistic beliefs.