STM32 reads IO high and low level status

With PC13 For example ：
If it is set to input ：
GPIO_ReadInputDataBit(GPIOC,GPIO_Pin_13);// Read input port PC13 value
If set to output ：
GPIO_ReadOutputDataBit (GPIOC,GPIO_Pin_13); // Read input port PC13 value
I look at the original function , The difference between the two read functions is that the read registers are different , Namely ：
GPIOx->IDR
GPIOx->ODR