The major difference between these two types is the rhyme scheme. The octave of a Petrarchan sonnet generally follows this form: ABBAABBA, where each letter represents one particular end rhyme for that line. ... The English sonnet, in contrast, has a rhyme scheme of ABABCDCD EFEFGG (the final two, rhyming lines are known as a heroic couplet, bee-tee-dubs). ... The octave is like an English sonnet, and its rhyme scheme is ABABCDCD. The sestet, however, takes the form of a Petrarchan sonnet and has a rhyme scheme of EFGEFG. ...