In fetal circulation, the ductus arteriosus and foramen ovale:
take blood from the fetus to the placenta.
connect the pulmonary artery with the aorta.
shunt blood from the right atrium into the left atrium.
bypass the lungs.

BYPASS THE LUNGS

Explanation:

Ductus arteriosus and Foramen ovale functions in the fetal circulation by shunting the blood from the right atrium into the left atrium and right ventricle through the pulmonary artery into the aorta respectively thus bypassing the pulmonary circulation, the lungs.

The major difference is that foramen ovale is and opening between the right and left atrium, and some blood flowing from the right atrium moves into the left atrium through this opening, bypassing the lungs.

Whereas, some of the blood do not pass through foramen ovale and enters the right ventricle, ductus arteriosus allows the passage of blood from the right Ventricle through the pulmonary artery into the aorta away from the lungs.