It's essentially a piggyback tune with no warranty vs a flash tune with a warranty. So it comes down to flash vs piggyback.
Here is a thread with a decent (somewhat) explanation of the difference -
https://f10.m5post.com/forums/showthread.php?t=1248685
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Wife's Car: 2020 X4M Competition, Alpine White on Black Alcantara and Biege
Current Car: 2018 F80 M3CS, SMB, DCT, ZEC, MPE
Recently Departed: 2020 F87 M2C, LBB, ZEC, 6MT (Euro Delivery Aug. 29, 2019, totaled by an idiot in a Camry who then ran from the scene)
Wife's Prior Car: 2018 F80 M3, Yas Marina Blue, DCT, Black 19s, Carbon Structure Anthracite Cloth/Leather Combination, Driving Assistance Package (Euro Delivery Oct. 9, 2017)