The second driver is the one that is obtained from the vendor directly, as I did when I went to Epson's website. The problem is that only this vendor-specific driver offers support for all of the printer's features. I was still using the Apple-supplied driver because simply downloading and installing the software from the printer vendor's website does not change the selection in System Preferences. This is why Color Options was missing from my Print dialogs.
Adding to the confusion, nothing I found in any printer documentation from Epson made this distinction clear. Apple does mention this, but it's buried in another Apple support article: "OS X automatically uses AirPrint...when you add the printer. If...the Print dialog doesn't have settings for all its features, you [need to] change its setup." Unless you discovered this article and understood its implications, you would likely have no idea that such a choice was even available.
Assuming you find yourself in this (or similar) situation, the solution, as stated by Apple, is to switch to the vendor-specific driver. Here's how.
Let's start by assuming you are currently using Apple's AirPrint driver, but that you have also installed the vendor's latest printer software. Let's further assume that your Mac is communicating with your printer via your network using Wi-Fi or via a LAN port on your AirPort device using ethernet, not a direct USB connection. That said, we're ready to roll.
Go to System Preferences and select Printers & Scanners. Select the printer from the Printers list on the left. In the Location section to the right, the Kind item name should end in -AirPrint.
While you could ultimately keep both drivers, allowing you to switch back and forth as desired, let's assume you just want to keep the more full-featured one. To do so, click the minus (-) button at the bottom of the Printer's list to delete the current driver.
Now select the plus (+) button. From the pop-up menu that appears, check the Nearby Printers list. Chances are good that your printer will be there. Ignore this! Installing this driver will reinstall the unwanted AirPrint driver.
Instead, select Add Printer or Scanner.
In the Add window that opens, your printer should be listed. If so, select it this time. But don't hit Add yet. We're still not quite done.
Check the Use item at the bottom. It will probably say AirPrint or Secure AirPrint. Again, this is not want you want. This is essentially the same as selecting the AirPrint driver from the Nearby Printers list. Instead, click the item to get the pop-up menu to appear; select the item that is name of the printer (Epson WF-4630 Series, in my case). In the unlikely case that the printer name is not found, choose Select Software; ideally, you'll find the name of the printer in this more extended list. If so, select it.
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