Interior design is the art and science of understanding people's behavior to create functional spaces, that are aesthetically pleasing, within a building. Decoration is the furnishing or adorning of a space with decorative elements, sometimes complemented by advice and practical assistance.
nterior designer implies that there is more of an emphasis on planning, functional design and the effective use of space, as compared to interior decorating. An interior designer in fine line design can undertake projects that include arranging the basic layout of spaces within a building as well as projects that require an understanding of technical issues such as window and door positioning, acoustics, and lighting.