Digital Cushions & Lateral Cartilages
The above picture shows the softer fatty tissues on the left and the hard Fibro-Cartilage tissue on the right. In this comparison there isn't much difference in the lateral cartilages, but bigger blood vessels can be seen on the right side of the right hoof.
In the video below you will see a much bigger difference between the Digital Cushions, Lateral Cartilages and the Blood Vessels.
The digital cushion is an important part of the hoof as it serves as a shock absorber for when the horse lands on that foot.
In properly exercised horses (24/7 turnout will help too), the hard Fibro-Cartilage tissue will give the horse comfort in the back of the foot. In horses with little to no exercise the soft fatty tissue of the Digital Cushion is typical.
The soft fatty tissue goes hand in hand with a thin lateral cartilage and hardly any blood vessels can be seen. The hard fibrous tissue on the other hand, is accompanied by thick lateral cartilage with multiple large blood vessels clearly seen.