The new entry-level SKU is $300 to $400 cheaper than the current UX331UN SKU by axing the dedicated GPU and halving both the LPDDR3 RAM (16 GB to 8 GB) and internal M.2 storage (512 GB to 256 GB).
https://www.notebookcheck.net/Asus-ZenBook-13-UX331UA-now-shipping-for-800-USD.320984.0.html