Art has always had its fashions, but has it ever been so fashionable as now? Glossy magazines are full of openings at London galleries – Timothy Taylor, Hauser & Wirth, a brace of White Cubes and Gagosians – attended by the gratin of our day: footballers, television personalities, minor royalty. Hoxton is artistic and fashionable, and it is far from easy to separate the two. From the other side, fashion has increasingly come to look artistic, couture shows aping performance art and the clothes in them sculpture. So an exhibition subtitled Art Fashion Identity makes the heart sink a little, suggesting as it does feverish egos, sloppy thinking and Jimmy Choos.
Actually, Aware, the latest in the GSK Contemporary series, isn't as bad as it sounds. Yes, there are half-hearted attempts to hint that art and fashion might be interchangeable, but this is restricted to the token works in the show made by fashion designers rather than by artists. (Contrary to the claims of Aware's curators, there is a difference.) Yohji Yamamoto's Femme Collection is wooden in more senses than one, the designer's timber-frock-as-a-sign-of-womanly-entrapment being both literally and metaphorically clunky. Alexander McQueen's red-lace dress with built-in veil comes from a 1998 show inspired by the burning of St Joan of Arc. It is beautifully tailored, sexy in a Hans Bellmer way and satisfyingly impractical. But while the making of unwearable frocks may result in useful fashion prototypes, it does not lead to art.
What is the difference? Let us start with that high priest(ess) of the art frock, Grayson Perry, otherwise known as Claire. Facing you as you climb the stairs of what used to be the Museum of Mankind is Perry's Artist's Robe (2004), a magician's cloak with ceramic buttons and heavily embroidered with alchemical signs. Artist's Robe is about all kinds of things – the esoteric nature of creation, the act of making, craft, Perry's fondness for dressing as a woman. More than these, though, it is about the human need to be clothed.
Where Yamamoto and McQueen start from the outside, using the body as a handy hanger for metaphors, Perry starts from the inside, from the personal and visceral, and works outwards. The result is that Artist's Robe is art, McQueen's little red-lace number just a frock. Any resemblance of fashion to art is minor and coincidental, even if the GSK's curators trade on it to plump up visitor numbers. More people read fashion magazines than go to art galleries, after all.
One thing Aware does do is point out the number of contemporary artists who work with clothing (as opposed to fashion). Where the Renaissance was fascinated with the nude, our enthralment has been with the clothed. For Yinka Shonibare MBE, cloth is part of history, his batiks telling both a generic story of post-colonial trade and another of himself as an Anglo-African. As with the flouncy hoop-skirts of Grayson Perry, the very last thing that Shonibare's Little Rich Girls bothers itself with is fashion, except, perhaps, in an anthropological sense.
Nor can the word "fashionable" really be applied to the deterministically named Gillian Wearing's Sixty Minute Silence, in which 26 people, dressed as policemen and ranked in rows as if for a class photo, try to sit still for an hour. For Wearing, clothes are an attempt to impose sameness by overriding the individualism of the body. As the various twitches and scratchings of her subjects show, however, bodiliness will always win out over uniforms – a typically quiet Wearing observation with huge ramifications for power and governance.
There are some lovely things in this show, most eye-catching among them Susie MacMurray's Cruella de Vil ballgown of dressmakers' pins, a neat elision of fashion and fashioning which calls to mind Louise Bourgeois at her blackest. I was also taken by Dai Rees's Carapace: Triptych, made up of three Francis Bacon-ish sides of beef made of handsomely cured leather. Is there an antonym for "recycling"? There is something grotesquely elegant about killing a bull, flaying it, curing its hide and reassembling it as a bull's carcass. From the number of oddly dressed visitors at staring at Carapace the day I went, I fear we may see some take on Rees's installation sashaying down the catwalk next season.
To 30 Jan (020-7300 8000)
Charles Darwent squares up to Mondrian at the Pompidou Centre.