The difference between white-lipped turtles and red-faced turtles is very simple. Just look at the bottom plate. Usually the ones without patterns are white-lipped turtles, and the ones with patterns are red-faced turtles.
It should be noted that only when they are young, the two are relatively similar, and when they grow up, they can see obvious differences, as Their names are the same. The white-lipped turtle has a white mouth and a black-yellow head, while the red-faced turtle has a red head, making it easy to distinguish.