AIFF and WAV files are pretty much identical except for the headers. All things being equal, they’ll be the same size. Sometimes things aren’t equal………
You MAY have mono versus stereo or you may have 22.050 kHz versus 48 kHz sample rates in either AIFF or WAV. You could also have 16-bit or 24-bit in either format.
Some editing software (older stuff) is pickier about file types. Other software is more flexible about combining different file types, sample rates and bit lengths.
There’s probably a window in which you can see the specifics of the particular avid session you’re working on. It probably shows what audio format was chosen when you started the production.
Regards,
Ty Ford
Ty Ford’s “Audio Bootcamp Field Guide” was written for video people who want better audio. Find out more at https://www.tyford.com