Not necessarily better, just different. Here are the main differences.
Impermeable to oxygen
Have performed admirably as the industry standard for decades
Shatter when dropped (don't drop!)
Better-Bottle fermentation carboys
Unbreakable and tough
Taste- and Odor-free
Virtually impermeable to oxygen
Clear and colorless
Incredibly light weight, and more . . .
They are made from special, scientifically tested, polyethylene terephthalate (PET) copolymer plastic that is non-absorbing, non-porous, and non-wetting (hydrophobic), so it does not carry over flavors from one batch of wine or beer to the next and is easy to clean and sanitize.
Optional racking adapters and valves make oxygen-free racking and dispensing simple and convenient – no siphoning is necessary. Optional closures that use O-rings to make tighter seals are more easily cleaned and sanitized than conventional stoppers.
Easily Scratched (no carboy brushes allowed!)
Will deform if cleaned with very Hot water (use warm water only!)