Alliteration is the repetition of consonant sounds at the beginning of words within a phrase or sentence.
Repetition of beginning a line is a poetic device known as anaphora. Anaphora involves the repetition of a word or phrase at the beginning of successive clauses, sentences, or lines to emphasize a point or create a rhythmic effect.
Example of alliteration:
* "Peter Piper picked a peck of pickled peppers."
Example of anaphora:
* "I have a dream that my four little children will one day live in a nation where they will not be judged by the color of their skin but by the content of their character. I have a dream today! I have a dream that one day down in Alabama, with its vicious racists, with its governor having his lips dripping with the words of interposition and nullification, one day right there in Alabama little black boys and black girls will be able to join hands with little white boys and white girls as sisters and brothers." (Martin Luther King Jr.)
Key difference: Alliteration focuses on consonant sounds, while anaphora focuses on the repetition of words or phrases at the beginning of lines.