There are a number of speech errors that are common among children learning to talk. These errors are a normal part of a child’s development, and typically resolve as a child matures. We only have concerns if your child is making errors more typical of a younger child or errors that do not fit a typical developmental pattern.
A speech sound disorder is an umbrella term that refers to both articulation disorders and phonological disorders. A child with an articulation disorder has difficulty achieving the correct placement of their lips, tongue and/or jaw to create clear, easy to understand speech sounds. This is more physical in nature.
A child with a phonological disorder has difficulty understanding the rules of a language’s speech sound system, so this is more linguistic in nature. It is not uncommon for a child to have an articulation disorder and a phonological disorder together.