Sectional sofas can break up an especially long, narrow space with their L, U or arc shapes. This also creates a small, cozy nook. They may work well for entertaining if one or more of the seats faces the others. However, a small sofa can be placed perpendicular to long walls to create a nook in an especially cramped space that might not accommodate a sectional.
While a sectional sofa may offer extra seating or a lounging area, sofas typically offer more flexibility in terms of where you can place it. A large ottoman can create a lounge chair when desired and tucked away when not in use. Some models offer hidden storage as well.
While both a high quality sectional sofa offer comfortable seating, personal taste and layout play an important role. The corners of sectionals typically offer a large, comfortable sitting space which may work well for watching TV, but not as well for entertaining guests. However, ottomans can also be added to a sectional to form a double-lounge if it has a chaise, and if the chaise has a long arm along its length, guests can sit with facing to the side instead of straight ahead.
Sectionals and sofas are both available in a wide range of design styles, colors and fabrics. However, a smaller sofa also allows you bring in eclectic chairs, cushions and throw pillows where you might not have room for additional furnishings with a sectional. However, some sectionals can be split apart quickly or arranged in different ways for more flexibility -- though some feature linking hardware and unfinished ends that make them unattractive when broken up. They can also serve as a unifying design element in a room with varying colors or patterns in carpet, paint, curtains and accent decor.