What are the differences between Kerdi board and cement board, and which one is more suitable for my project?

Kerdi board is a lightweight, waterproof foam board, while cement board is a heavier, water-resistant cement-based board. Kerdi board is better for wet areas like bathrooms and showers due to its waterproof properties, while cement board is more suitable for general use in areas that may not be consistently wet. Consider using Kerdi board for your project if you need a waterproof solution, and cement board if water resistance is sufficient.