Answer:
Here's an example you could change up and borrow;
Photosynthesis and Cellular Respiration are (etc). They both take part in a process involving plant growth and (so on); however, they can be very different. Photosynthesis is... (define). Cellular Respiration is.. (define). This will tell you what Photosynthesis is, Cellular Respiration, and the differences and similarities of the two.
I'm not the best at introductions myself, but I use the best that I have got!! You got this :))