Definitions
Comprehension - is the words and word combinations that children understand.
Production - is the words and word combinations that children use.
Production - is the words and word combinations that children use.
Distinction Between Comprehension and Production
At all ages in life, comprehension develops ahead of production. There is a five-month lag between the time toddlers can comprehend 50 words and the time that they can actually produce that many. Comprehension requires children to recognize the meaning of a word. But in the light of production, children must recall or actively retrieve from their memories. They not only have to remember the word but also the meaning of the word. These two concepts are still related. When a child's speed and accuracy of word comprehension is faster then they show a more rapid growth of words understood and later produced.
Berk, L. E. (2012). Infants and Children: Prenatal Through Middle Childhood. Boston: Pearson.