The blues stanza is a triplet derived from the Afro-American tradition of lamentation or complaint in which line two is an incremental repitition of line one and the third line is a climactic parallel, AAa, BBb, etc.
exerpt from example (author unknown):
The Shadowman
This is the year when everybody died - this is the year when friends and neighbors died, took that short trip or ended the long slide
jim shot himself on cemetery road, left an ironic note beside the road. no one heard his desperate heart explode.
A blues sonnet is fourteen lines consisting of four blues stanzas written in iambic pentameter meters and a herioc couplet: AAa BBb CCc DDd ee. There is a volta (turn) after the last triplet.
excert from example:
envoi (by wesli court)
just let me drop this note into the dark yes, let me drop this note into the dark i'll light it with a match and watch it spark
i'll sail into night with fire and flare, fly it into darkness, see it flare and wink out in those shadows circling here