There are several disciplines that are hard to describe as either being sciences or arts.
The first discipline that is hard to describe as either being a science or an art is the architecture discipline. Indeed, the nature of architectural training is such that the people going through it have to be taken through rigorous courses of training in both the arts and the sciences. By the time they graduate, it is hard to classify them as being either purely artists or purely scientists.
The second discipline that is hard to describe as either being a science or an art is the general design discipline. To the extent that the designers make use of their creative faculties, they are regarded as being artists. And to the extent that they designers have to adhere to certain standards of precision in their work, they are regarded as being scientists. It is hard, in the final analysis, to classify the people who design 7 passenger vehicles like the Mazda car or the Dodge van as either being artists or scientists. Looking at the interior design aspect, you get a feeling that they are artists. Looking at the exterior design aspect, you get a feeling that they are scientists.