Final answer:
Transverse waves have crests and troughs, while longitudinal waves do not, as their disturbances are perpendicular and parallel to the direction of wave travel, respectively.
Step-by-step explanation:
Two characteristics of transverse waves that are not found in longitudinal waves are crests and troughs. Transverse waves feature a motion where the disturbance in the medium is perpendicular to the direction of the wave's travel, hence they have crests (the highest point of the wave) and troughs (the lowest point). In contrast, longitudinal waves have compressions and rarefactions instead, as the disturbance travels in the same direction as the wave, characterized by areas where the medium is compressed or spread out.