They are not necessarily better. Rather, different. Personal preference. This is not really a good deal. I highly strongly recommend that anyone demo these headphones if they can, but also the rest of the DT Pro range. Subtle differences, 880s are open back which has pros and cons. Basically, get the ones that sound right for you. But be assured this is a ruddy good range of professional level headphones. But this is an average price not a deal.
The DT990 are only £105 on Amazon
These are great but depending on the version this is the normal price or +£10. Still well worth it though. So comfortable and they sound great.
How is this price a deal? This has been their default price for years now
Open though so consider that (y)