What are the major differences between blood circulatory system and road transport system?

The blood vessels in the body are similar to roads in that they are both used to transport things that humans need.

Blood vessels support nutrients, and roadways like farm to market roads support the transport of foods. Vehicles on the road can be likened to blood cells. White blood cells would be like police cars and red blood cells would be like trucks or cars. Platelets would be like emergency response vehicles.

Blood vessels all intersect, however. There are no dead ends in a living organism, no pun intended. Roadways oftentimes have dead ends, and there are entire systems of roads that are not connected to each other.

Roads are usually two way, but blood vessels are not. All blood vessels are in a single direction, and all blood flows in one way.

Whereas cars and trucks provide their own speed, blood cells are all pumped by the heart, and move as one.