Over the years working as a speech-language pathologist, I have often been met with confusion from caregivers when diagnosing or discussing a speech or language delay. I know it's important to help caregivers understand the difference between what we mean by "speech" and what we mean by "language".
In simple terms, speech refers to the how we make sounds to produce words. The American Speech-Language Hearing Association (ASHA) identifies 3 key aspects of "speech" which include articulation, voice, and fluency.
Articulation refers to the way we move our tongue, lips, and mouth to make sounds. For example when we articulate the L sound we lift our tongue to the ridge behind our upper teeth.
Voice is another way to say "vocalizing" and refers to how we use both our breath and how our vocal cords (vocal folds) open and close to produce the sound we hear.
Fluency refers to the smoothness, rate, and how effortful our speech is. Stuttering impacts one's fluency.
Language refer to words and how we combine them into phrases sentences and the meaning of those words, phrases, and sentences. Language is how we communicate our wants, needs, and ideas. We use the terms receptive language and expressive language to differ between understanding of language (receptive) and using language to express ourselves (expressive).
American Speech, Language, Hearing Association. (n.d.) What is Speech? What is Language? https://www.asha.org/public/speech/development/speech-and-language/