What is the difference between er and vegetable oil spread?

Hi i just recently moved out and started cooking and im so confused about er/margarine/vegetable oil spread... i've bought country crock,bluebonnet,and other brands that say both btuter and margarine and the most recent one i bought was 50% vegetable oil spread because it was big and cheap... ive used it for everything...cooking..on pancakes and it tastes fine but i just read online that it would be bad to make in say.. cookies and i was wanting to make some. Can someone explain the difference in all 3 and what they are used to cook?