Cases are associated with meaning or usages and with constructions. However, they almost never have a single meaning or use, nor are they the only way to express a given meaning. Thus, the Dative may express "purpose" or "possession" or "personal interest in an event", and similiarly "possession" may be expressed by the Dative or the Genitive or a relative clause, etc. A precise analysis will say that they are never the only way to express a meaning (you can always put in "in other words"), but they are the only way to express a syntactic relationship (which may themselves indicate different meanings).
Thus, the only one way to express the direct object of a transitive verb is the accusative case. Similarly, there is only one way to express the person 'indirectly' interested in an action: the dative case. However, the meaning "I please you" can be expressed either as a transitive verb with a direct object: delecto te, or as an intransitive activity with you as the beneficiary: placeo tibi.
Although most of us would grant that for practical purposes delecto te and placeo tibi are "synonymous", when we care to be more nuanced, we might sense that delecto te is more active or more like something done purposefully, while placeo tibi seems more to emphasize a state that is pleasing "to you." These considerations are not merely philological. Luce Irigary has written a book on the love and gender relations titled, I love to you. She chose this title because she felt that "I love you" had turned love into something you do to someone, as you might hit a ball or bake a cake. She felt that "I love to you" presented a more equal and ideal relationship, on in which loving had a goal or an aim, but not necessarily a transitive effect. It is interesting to the philologist that in changing the modern idiom (she wrote in French) she has retraced linguistic history and arrived at the original meaning of the accusative case.