Artery:

(i) It is a thick walled blood vessel.

(ii) It carries blood from the heart to different parts of the body.

(iii) It can dilate or constrict depending the regulatory requirement of the body.

(iv) It does not contain any valve.

Vein:

(i) It is a thin walled blood vessel.

(ii) It brings blood from the different parts of the body to the heart.

(iii) It cannot dilate or constrict.

(iv) It contains simple valves which permit blood flow only towards the heart.

Capillary:

(i) It is an extremely narrow blood vessel having very thin walls.

(ii) They form an extensive network throughout all living cells in the body and connect arteries and veins.

(iii) It can dilate or constrict according to the requirement of the tissue.

(iv) It does not contain any valves.