Stuttering is a communication disorder involving disruptions in the forward flow of speech. The word "stuttering" can be used to refer either to the specific speech disfluencies that are commonly seen in people who stutter or to the overall communication difficulty that people who stutter may experience.
Articulation is the oral motor movements during the production of speech sounds. Articulation disorders are those speech deviations that involve substitutions, distortions, omissions, and/or additions of speech sounds.
A lisp is a functional speech disorder. A functional speech disorder is a difficulty learning to make a specific speech sound, or a few specific speech sounds. A lisp is a mispronunciation or distortion of the /s/ and /z/ phonemes (speech sounds). There are generally two kinds of lisps: frontal and lateral. The tongue protrudes forward with a frontal lisp. With a lateral lisp, the tongue moves to the side for speech sound production.