After looking at enough art over the years the difference between a sketch and a study might seem pretty obvious, but the definition (at least for me) was really a guess based on accumulated experience. The problem with this method is that calling an artwork a sketch or a study seems completely arbitrary, relying on the understanding of each individual artist as to what they think the difference is. The result is an extremely fuzzy classification system, where a sketch or a study just means any artwork that is not a finished work.
But, I was happy to find out that there is a difference and what the purpose for each one is.
A sketch is the main idea. Whether it is a painting, a drawing, or even a sculpture, a sketch is where the artist explores the composition for the final work. Accurate draftsmanship, color, and detail are not important in a sketch. The most important thing is to get down the main idea, the impact, and the spark that ignited your passion to make the artwork. A sketch is about the big things in an artwork.
On the other hand, a study is the complete opposite of a sketch.
Studies are fussy. However it is made, a study is all about gathering information. When making a study of a scene or an object be as accurate as possible. Put in all of the details that might be important. Composition and emotion don’t count in a study, accuracy of color and draftsmanship do. A study is an objective notation of observed facts.
Together, sketches and studies are the pillars of support to help make the final artwork.