Here’s a simple Venn diagram comparing and contrasting the Petrarchan (Italian) sonnet and the Shakespearean (English) sonnet. Let’s break down the diagram to look into these similarities and differences in more detail.
Both styles are characterized by the usage of iambic pentameter, a type of poetic meter in which each line consists of five iambs. An iamb is a pattern of a short or unstressed syllable followed by a long or stressed syllable (as heard in the word “today”). All sonnets are composed of 14 lines and thematically include a technique called the volta ("turn"). The volta represents a shift in style and content/theme.
The Petrarchan sonnet’s structure includes an octave (a set of 8 lines) followed by a sestet (a set of six lines). The rhyme scheme is tied to this structure; the octet will follow an ABBAABBA pattern, while the sestet can vary (CDDCDC, CDECDE, CDCDCD, etc). The volta occurs at the ninth line, at the beginning of the sestet, and represents the shift from the problem presented by the octave to the resolution presented by the sestet.
The Shakespearean sonnet is divided into four parts rather than two. The bulk of the sonnet is made up of three quatrains (sets of 4 lines) followed by a couplet (a set of two lines). The rhyme scheme changes with each section, following ABAB CDCD EFEF for the three quatrains and GG for the couplet. The overall structure is more flexible, and the volta can occur anywhere. It’s common for the volta to take place in the final couplet, and it is used to present a sharp contrast to whatever has been discussed during the quatrains. When utilized in this way, it packs more of a punch than the Petrarchan sonnet, which has 6 lines to elaborate on the thematic shift of the volta rather than two.