Two different construction styles are typically used for building cabinets.  Face frame construction has been the construction style used in this country for years.  In recent years, frameless construction, which originated in Europe,  has been increasing in popularity.  There are variations of each type, and the end result can actually look very similar as seen in the photos below.  There is no difference in the quality or durability of the cabinets either way if properly constructed.  Frameless construction is slightly less expensive than face frame, and better utilizes a given space.  However, sometimes face frame construction is required to achieve a certain appearance .  An example of this is with beaded inset doors and furniture feet.   
This is an example of frameless construction.  There is a 1/8" reveal between all doors & drawer fronts,  and between the doors and panels that form the finished ends of the cabinets.  Typically, the end panels are designed to match the doors. 
The fillers and light valance on the upper center unit produce the effect of inset doors since all components at the face of the cabinet are on the same plane.  With frameless cabinetry, concealed hinges are always used.

   (click on image for larger view)
This is an example of face frame construction style with inset doors.  With an inset door, the front of the door is on the same plane as the front of the face frame.  In this situation a visible hinge was used to achieve the desired appearance, but a concealed hinge could also be used to achieve the appearance as above.

    (click on image for larger view)