Dearth noun – A falling short of an essential or desirable amount or number. Sparsity and dearth are semantically related in lack topic. In some cases you can use "Sparsity" instead a noun "Dearth", when it comes to topics like insufficiency.
Sparsity noun – The property of being scanty or scattered; lacking denseness. Dearth and sparsity are semantically related in lack topic. You can use "Dearth" instead a noun "Sparsity", if it concerns topics such as deficiency.