When a person is unable to produce speech sounds correctly or fluently, or has problems with his or her voice, then he or she has a speech disorder. Difficulties pronouncing sounds, or articulation disorders, and stuttering are examples of speech disorders.

When a person has trouble understanding others (receptive language), or sharing thoughts, ideas, and feelings completely (expressive language), then he or she has a language disorder. A stroke can result in aphasia, or a language disorder.

Source: www.asha.org