Infertility vs Barren

This may be a stupid question but is it the same thing? I was told if you were infertility you can't have babies at all but when people talk about it on this app they say they may have been infertile for an amount of time and then was able to conceive a baby or they took something to conceive. I'm just confused on the terms I know baron women can't have children. I just wanted to know the difference is all its confusing to me when I read posts about infertility. Not trying to hurt feelings here just grasp an understanding.