What is the difference between medium and working gaits?

Working trot or Trot: the natural trot of the horse when under saddle. The stride length is "normal" for the horse ;some breeds have naturally shorter or longer strides. It is a gait between the collected trot and medium trot. Medium trot is a trot that is more engaged and rounder than the working trot, with moderately extended strides. It lies between the working and the extended trot. The horse has good, solid impulsion. Hope that helps.