Structurally speaking, a senryu does not differ much from the haiku. But take into account the theme of the senryu, and you’ve got a whole other story.
The senryu, like the haiku, follows a 5/7/5 meter (which is, by the way, optional), and has a kireji (a cut in the poem that introduces another element). The difference is that a senryu features usually (but not always) humorous human follies, in contrast to the haiku’s kigo (an indicative seasonal word or phrase).
Grayish amber eyes
Scintillating in the dark–