A link is a physical or conceptual connection among objects. For example, Joe Smith WorksFor Simplex company. Most links relate two objects, but some links relate three or more objects.
An association is a description of a group of links with common structure and common semantics. For example, a person WorksFor a company. The links of an assiciation connect objects from the same classes. An association describes a set of potential links in the same way that a class describes a set of potential objects. Links and associations often appeat as verbs in problem statements.