Based on the provided content, the difference between speech and functional communication skills lies in their scope and purpose:

Speech refers to vocalization and the production of spoken words. While the text mentions Vocal Imitation Training to help children who are beginning to produce sounds, it emphasizes that functional communication goes far beyond just spoken words.

Functional Communication Skills represent the broader ability to express basic wants, needs, and feelings in a way that others can understand. Key distinctions include:

• Modality: Functional communication is not limited to speech; it includes using the Picture Exchange Communication System (PECS), Sign Language, Augmentative and Alternative Communication (AAC) devices, and gestures.
• Purpose: The primary goal of functional communication is to allow a child to initiate requests, protest unwanted activities, comment on experiences, or engage in social exchanges to reduce frustration.
• Behavioral Impact: Unlike the simple act of speaking, Functional Communication Training (FCT) is a specific intervention used to identify the “why” behind challenging behaviors (like tantrums) and replace them with appropriate communicative acts.

• Functional Communication Skills: Complete Guide to ABA Therapy Benefits