When I was in art school, the most dismissive thing that could be said during a critique was that the work was ‘decorative’.  No one ever really explained exactly what this meant, but it was clear that this ‘decorative art’, no matter how well executed, was always going to be a lesser art, subservient somehow to the real thing.
‘Real Art’, ‘Fine Art’ or ‘Serious Art” are all terms that get thrown around to describe the alternative to ‘decorative’ (or, commercial! Gasp!).  I don’t happen to like any of these terms as they seem arrogant and pretentious.  But I do think that there is a difference.

Here, I think, is the essence of it:  One type of art is about the image and the reaction that the image provokes (often, but not always beauty).  In this type, each image stands more or less on its own.  I think in this case of a gallery that I walked into one time with an exhibition of sunflower paintings.  Some times turned this way, sometimes that, all with the same color pallet and lighting.  Nice paintings, well executed.  Each a complete, totally self contained image.
The ‘other’ type of art is about the image AND the artist.  Here the artist has an idea, creates a piece that expresses that idea, and that creation somehow informs the next image.  It may be in a refinement of the idea, in the marks, in the color or in the technique.  The individual image may be striking, but it is in the series of images that you see the struggle of the artist with the idea or the medium, or the intersection of the two.
I am reminded of the room in the National Gallery in London where there are four of Monet’s ‘Haystack’ paintings side by side.  Each, by itself, is a lovely image, but the four together tells you much about what he was thinking about, looking at, and learning about.

I do not think that ‘decorative’ art (my first type) is inherently inferior to this second type.  There are clearly more and less talented artists working in both spaces, and thus the quality varies.  I am also somewhat at a loss for a term to describe this second type.  Most of the words that are used (or that I can think of) seem self important.  Exploratory Art?  Inquisitive Art?  You choose.