Chhand refers to rhythmic patterns, while lay defines the speed of a composition. Chhand creates variations within a taal, while lay determines if the rhythm is slow (vilambit), medium (madhya) or fast (drut).
Class 6 Arts Kriti-I Chapter 8 Taal or Talam and Raga or Ragam in Indian Music NCERT solutions
Class 6 Visual Arts Kriti-I Taal or Talam and Raga or Ragam in Indian Music question answer