A bridge is an exercise primarily for the neck where you support your bodyweight with your head and feet only while in a supine(face up position.You can also do it face down).The move developed in wrestling and can put severe stress on the neck and spine if you are not careful.
Planks are an abdominal exercise where you are face down on the floor and your body is supported by your feet and forearms only.You contract the abs hard and hold for a designated period of time.It's a good finishing move for the abs.
How do you do bridges and what muscles are they for? i've also heard them called planks.
do side bridges (on one elbow, side of one foot) for a good oblique workout. i noticed a big diff after a few weeks of doing them. hold it as long as u can, and suck in that gut while doing them. if u train with someone, and you notice that after 40 seconds or so it still isn't burning, have a buddy put a 10-20 lb plate on your back.