They were probably about the same height, skin color, eye color and hair color. What made them look different was their hairstyles and clothing.
Saxons wore simple tunics. The women and girls wore floor-length tunics (under-tunics and top tunics) and the men and boys wore knee-length tunics. The men wore breeches under the tunics. They wore cloaks when it was cold outside. They would embroider their best tunics around the cuff and collar, and perhaps the circular hem.
Norman men and boys wore longer tunics with a split in front and back to accommodate horse-riding. The collar of the tunic was also split lengthwise for room. They also wore breeches under the tunic and cloaks for warmth. The women wore more fully cut long dresses at floor length.
The hairstyles were very different. Saxon girls wore their hair down until they were of marrying age. Then it was braided. In the 12th century in 2 braids. The Saxon men wore beards, mustaches, and long hair in a single braid. Norman women wore their hair under veils. I don’t know if it was up or not. The Norman men cut their hair short and shaved off facial hair, at least when they were at home and could.
You will find good illustrations in books of Saxon and Norman appearance at your local library.