Well, sort of. If you have a wav file and an mp3 file, both of which have a sample rate of 44kHz, they will both be able to represent the same maximal frequency of 22kHz. The mp3 wouldn't necessarily discard the high frequency information, but it may do so when it is deemed that the sound wouldn't be perceivable.
However, MP3s throw more high frequencies than the digital signal at that given sampling rate allows.