What is the primary difference between a Spenserian sonnet and a Shakespearean sonnet?

The primary difference between a Spenserian sonnet and a Shakespearean sonnet lies in their distinctive rhyme schemes. A Spenserian sonnet features a rhyme scheme of ABAB BCBC CDCD EE, where the interlocking structure connects the quatrains in a unique way, allowing for a more thematic development across the poem. In contrast, a Shakespearean sonnet employs a rhyme scheme of ABAB CDCD EFEF GG, which culminates in a decisive couplet at the end.

While line length and stanza structure are common elements in both sonnet forms, they remain consistent across sonnets generally. Each sonnet type consists of 14 lines written in iambic pentameter, and they both have a similar structure of three quatrains followed by a couplet or an alternative arrangement. Thematic elements, while possibly varied between individual poems, do not fundamentally distinguish these two forms of sonnets, as poets often explore similar themes in both types. Thus, it is the rhyme scheme that is the essential distinction separating the Spenserian sonnet from its Shakespearean counterpart.