Is a .FLAC lossless audio file the same as a .WAV lossless audio file? If not what are the differences?

The .wav format isn't considered "lossless" because the format is not compressed in any way. The term "lossless" refers to digital audio file compression that doesn't lose any audio information, unlike MP3 files which are "lossy." FLAC files are .wav files that are compressed without losing any audio information. FLAC files are usually around 33% smaller than its original .wav file.