Is there a separate term for confectionery art?

Solution 1:

The term you may be after is sugarcraft

The art of creating confectionery or cake decorations from sugar paste. [ODO]

There's a British Sugarcraft Guild, who have images such as these to illustrate particular examples of their members' confectionery art:

(Both images from British Sugarcraft Guild)

The term appears to be well-established, although it may be mainly British.

Solution 2:

As far as job titles go:

Cake Artist or Cake Designer are both good options.

I usually say "cake artist" but now that I think about it, how about "pastry artist?"

I call myself designer/baker.

I am a Professional Baker and Cake Designer

Taken from this discussion among cake 'designers', there are a few other ideas there too.

As per Lawrence's comments, if you were looking for phrases to describe "the discipline" versus the job title, then you could modify the titles like so:-

Cake Artist --> Cake Artistry
Cake Designer --> Cake Design

Solution 3:

The term cake decorating covers the mid-to-elaborate range of cake art, a subset of confectionery art.

Cake decorating is one of the sugar arts that uses icing or frosting and other edible decorative elements to make plain cakes more visually interesting. Alternatively, cakes can be molded and sculpted to resemble three-dimensional persons, places and things. - wikipedia

Food presentation spans a broad range that covers a superset of confectionery art.

Food presentation is the art of modifying, processing, arranging, or decorating food to enhance its aesthetic appeal. - wikipedia

For the term itself, your own confectionery art works. Have a look at the links for a pinterest page that includes elaborate sculptures and a competition that includes the words "confectionery art", called the International Confectionery Art Competition.