Congenital muscular dystrophies are disorders that have in common that they typically involve underlying impaired components of the extracellular matrix and/or sarcolemma. Impaired function of the sarcolemmal membrane is a reason these disorders are associated with elevated CK.
Impaired function of proteins of the contraction matrix and impaired function of excitation-contraction coupling are both most often associated with congenital myopathies, not congenital muscular dystrophies. Congenital myopathies often have normal CK.
Both congenital myopathies and congenital muscular dystrophies present very early in life (typically at birth or within 1 year) with hypotonia and weakness. They also have many differences. As a group, congenital myopathies typically show myopathic changes on biopsy (fiber atrophy or hypertrophy, degeneration/regeneration, displacement of central nuclei) while congenital muscular dystrophies show dystrophic features (fibrosis, fatty change, necrosis).