Final answer:
An Italian sonnet has an octave and a sestet with a volta between them, exemplified by "Sonnet 292" by Petrarch, whereas an English sonnet is structured with three quatrains and a final couplet, with "Sonnet 18" by Shakespeare as a classic example.
Step-by-step explanation:
An Italian (Petrarchan) sonnet and an English (Shakespearean) sonnet have distinct characteristics that differentiate them from each other. The Italian sonnet typically consists of an octave with the rhyme scheme abbaabba, followed by a sestet with variable rhyme schemes such as cdecde or cdcdcd. The volta, or turn in thought, usually occurs between the octave and sestet. An example is "Sonnet 292" by Petrarch.
Conversely, the English sonnet is comprised of three quatrains, each with its own rhyme scheme of abab, cdcd, efef, culminating in a decisive couplet at the end with the rhyme scheme gg. The volta can appear before the final couplet, typically highlighting a thematic twist or resolution. "Sonnet 18" by William Shakespeare is an iconic example of this form.