Question: what is the difference between a monitor lizard and an iguana?
Answer: Shape-Iguanas are thicker than monitors; monitors are more snake-like and have a narrower head. Spines-Iguanas have a row of spikes down their back. Monitors do not. The spines are more obvious on Green Iguanas than on Spiny-tailed Iguanas, though Spiny-tailed Iguanas also have spines on their tails.