Different materials can be used as a surface to mount tile on a wall. There is greenboard, cement board and cement and lath. If you are tiling above a bathtub or in a shower you should never use greenboard. It is not intended as a backer board for wet locations.
If you would like the chance to work with me or one of my fellow real estate investor coaches and our advanced training programs, give us a call anytime to see if Dean's Real Estate Success Academy and our customized curriculum is a fit for you. Call us at 1-877-219-1474 ext. 125