Most specific wall tiles are ceramic, making them not strong enough, specifically the glaze to be used under foot. All floor grade tiles can be used on walls. Wall tiles are usually used in wet areas to ensure the water proofing of bathrooms and ensuites.
You don’t have to tiles floor to ceiling in wet rooms outside the shower area, however we always recommend that you do to achieve a design result. If the budget does not allow floor to ceiling height tiling throughout, essentially you only need to do a skirting tile around the room outside the shower recess.