Haiku traditionally contains two contrasting images. One suggests time and place. The other is a strong, temporary observation. Together they form a new image - which is left for the reader to discern. Senryu is similarly constructed to haiku but is usually humorous or satiric and deals with the human perspective as opposed to nature.
Tanka is a Japanese verse form.
Tanka are mood verses, and use poetic devices such as metaphors and personificatin which are avoided in haiku. Traditional Japanese tanka consists of five lines of 5,7,5,7,7 syllables, respectively, to total 31 syllables. Whilst western and modern writers of tanka are generally haikuists, in Japan writers of tanka and writers of haiku are seldom the same person. Haibun is prose that shares the haiku angle of looking at the general through the particular, with haiku-like condensation in the prose style and incorporating at least one actual haiku. Renga, or renku, is linked verse where two or more poets write a series of verses.