My goal here is not to define with the precision of a research report but to explain for purposes of teaching. Alphabetic insight is the aha experience when children discover that word spellings tell your mouth how to say a word. By extension, the spelling of word is a map of the phoneme sequence in the pronunciation. Blending means smoothing together word parts to recognize a word.
Consonants are phonemes made by constricting the vocal channel enough to cause friction.
Correspondences are learned links between graphemes and phonemes, so that the grapheme triggers the phoneme when reading a word. Decodable texts are texts in which most of the words can be decoded using correspondences children have learned to date in their phonics program. Decoding means using the spelling of a word to reconstruct its pronunciation. Early decoding involves sounding out and blending, but later decoding takes only a fast and silent spelling analysis. Digraphs are graphemes written with more than one letter.