Bathtub refinishing coatings are designed to mimic the look and feel of porcelain. This is why refinishing is often advertised under bathtub refinishing. The truth is not only will refinishing work on bathtubs but also showers, tile, sinks and vanities.
When considering bathtub refinishing for the first time make sure you are getting actual bathtub refinishing and not bathtub painting. The difference will definitely be known within a few weeks, even if at first glance they do not appear that different.