What is the difference between desloratadine and loratadine?

Fundamentally they differ only in that desloratadine (decarboxyethoxyloratadine) is the major and more active metabolite of loratadine. Desloratadine have a very longer half life, approximately 24 to 27 hrs, than loratadine (aprox 8 hrs). Both are h1 receptor antagonists antihistamines, but desloratadine is moderately more effective and very long acting.

They are the same.

Desloratadine is used in the treatment of hay fever; urticaria and belongs to the drug class antihistamines.

Loratadine is used in the treatment of urticaria; hay fever and belongs to the drug class antihistamines.