Dear student,
Renal artery is a pair of large blood vessels that branch off from the heart and enter into each kidney. The renal arteries carry a large portion of total blood flow to the kidneys and adrenal glands and ureters.The blood which they carry contains a higher percentage of oxygen.
Renal vein are short thick veins that carry deoxygenated blood out of the kidney. They have very low % of oxygen. Regards