The flat self edge, or square edge, is a standard edge profile offered at no additional cost to you. This edge does have seams.
The waterfall edge is a standard edge profile offered at no additional cost to you. This edge has no seams as it is a continuation of the countertop.
The 180 or bull nose edge is an additional cost per linear foot for laminate countertops. The 180 edge allows for the laminate to wrap around the edge of the countertop, leaving the underside laminated and creating a rounded look.