Haiku or Senryu?
A haiku and a senryu can look identical on the page. The count is the same. What differs is where the poem points, toward nature or toward us.
Same shape, different gaze
Haiku and senryu are both short Japanese poems in three lines, and in English both usually follow the 5-7-5 count. The difference is subject and tone. A haiku looks outward, to nature and the seasons, and holds a note of stillness. A senryu looks at people, at our habits and vanities and small comedies, and it is often wry.
What a haiku does
A haiku records a moment in the natural world and lets it resonate. It leans on a season word and a cut between two images, and it avoids commentary. The feeling arrives sideways, in what is shown instead of what is said.
What a senryu does
A senryu turns the same brevity on human nature. It usually drops the season word and sharpens the irony, and it often ends on a small twist. Where a haiku is content to observe, a senryu has a point of view, and frequently a sense of humor about it.
When the line blurs
Plenty of poems sit between the two. A haiku can carry a flicker of humor, and a senryu can turn tender. The names describe a tendency, not a hard line. If you are unsure which you have written, ask where the poem's attention rests: on the world, or on the people in it.
Haiku Journal publishes haiku in the traditional 5-7-5 form. If you are still deciding what makes a haiku a haiku, start with what is haiku and the form, then read widely in the archive.