I found this simple discription of the contrast of the two forms on the web at: http://www.tnellen.com/cybereng/haiku/senryu.html Here is a short quote that I found especially illuminating..... At the simplest level, haiku are verse about nature and humanity, written in a 5-7-5 syllable pattern, while senryu are haiku-like verse, not necessarily about nature, not necessarily in that pattern. Sign in to see full entry.