So that gets a little weird. In one spot, the catalog says it comes with 128 GB of RAM. In another spot, it says it comes with 192 GB of RAM. It's either the same as the 16200 Plus with an added-cost RAM upgrade, or it comes with more than the 16200 officially supports at all.
It also says it comes with two 4x10g cards, LOM, both drives, and both power supplies. All are added-cost options for the 16200, and I think all are included with the 16200 Plus.
Finally, the QLS250's SSDs are 960 GB, while the 16200 and 6900 have 480 GB SSDs. This doesn't matter quite as much, since firewalls generally don't need a lot of drive space. Still, it's nice to have more headroom for snapshots.