Receptive language refers to what your child understands, such as demonstrating that he/she can follow verbal instructions, can point to body parts named, and answer simple questions correctly when asked.
Expressive Language refers to the form, content, and social use of language. Content of language refers to the vocabulary (inventory) of words that your child is using. Form refers to the way that your child is combining strings of words. Expressive language development progresses from cooing in infancy, to babbling, to first words (typically 12-14 moths). From 1.5 to 2 years, there is a rapid expansion in both vocabulary and word combinations. By age 2.5 years, children are most often producing 2-3 word phrases such as "Daddy work?", "What's that?". Children who have difficulty expressing themselves can become frustrated in trying to communicate, and behavioral issues can often occur.