This may be TMI, but here goes....
The x600, 4000, and 3800 printers were the first printers to use the Ulktrachrome inkset. The previous printers used pigments or dyes. These were also designed for dyes, but most didn't use them. The gamut range was closer to the dye prints, and much better than the original pigments from the P2000, 5000, and x500 printers they replaced.
The x800 machines from about 2005 were the Ultrachrome K3 inksets. This gave you PK or MK with LK and LLK. To go from Photo to Matt ink requires time and lots of ink. For b&w, these printers set the standard, IMO.
The x880 machines that replaced these (same inks as your 3880) have the Vivid Magenta and Vivid Light Magenta change for better stability and color and the head was improved to create less clogging. Pretty much the same printer as the previous in look.
I believe the inksets with the exception of the VM and VLM are the same between the these printers and both in 110ml and 220ml.
In each of these and back to at least the 4000, 7600, 9600 all share the same cutting blade, great for paper, not for canvas.
The x890 has pretty much the same inkset as the previous, but new carts in the HDR series, 150ml, 350ml and 700ml. The inkset seems to be the same at the x900 except that the x900 series adds Orange and Green to the mix for expanded color gamut.
Both the x890 and x900 printers have both PK and MK installed and switch dumping a couple of ml of ink in the swap like your 3880.
Both also have the thick-media (canvas) rotary cutter and the spectrometer can be added for profiling, generally used in prepress, 360 nozzle head (x800 & x880 has 180 nozzles), and a spindleless paper system.
I have and use a 7600, 9800 and now 9900. Each is a step-up from the previous. The 7600 is a little workhorse and though slow, has pretty good image quality. The 9800 is double the speed and for b&w is a step up overall. The 9900 is the best of the three. About twice as fast as the 9800, a rotary cutter for canvas, no more spindles, better info on the display, etc.
The 7600 took a little time to set-up and get going. The 9800 was a little easier, the 9900 was the easiest printer of the three for getting connected to my Mac network.
Since the x800 series, each printer comes with a stand and Ethernet standard. These were options before.
On the other hand, the 7600 shared the same ink carts as my 4000. If I needed a cart in a hurry, I just swapped them. Both were pretty easy to set up since they were relatively lightweight and compact. The 4000 had its own channel for MK and no switching between the two. When Epson replace the 4000 with the 4800 and the 4880, no more cart swapping between the 7800/9800 and the 7880/9880 since the larger printers pressurize the carts to keep the ink flowing.
The 9800 was, of course larger and heavier to set up. The behemoth is the 9900. It's longer, taller and a lot heavier than my 9800. It was like taking a coffin down the stairs and took 4 people. The 9800 was manageable with two.
The info on the 9900 tells you to the 1/10th ml the ink consumption per print. This is one hellua printer!
All these printers do take one part in common, the ink waste tank remains the same.