What are ceramic and plastic gold legged ic chips?
Quartz display and gold inlay?
What is an EPROM chip considered?

The plastic and ceramic gold legged or gold capped ICs are a new special class for certain ICs that can't quite fall into a higher CPU class but still have more value than an IC normally. Some are oddball, some are manufactured differently for special socket or order

Quartz display with gold inlay are ceramic ICs commonly found from scanners, old monitors, T.V.s, and stereo equipment. The IC is generally longer than normal. It is usually ceramic but not always. It has a full glass or quartz window, which displays the internals and die inside. A look inside the window will show you the gold inlays and gold tethering's. Most gold inlay ICs are gold pinned as well, but not all.

An EPROM is a common IC. Package is ceramic or plastic. Identified by the glass square window on top of the chip; Used for UV light to reprogram the IC. It is your older uncle to the newer used EEPROM which is practically the same physically but not internally. EEPROMs are electronically programmable (MOSFETS) controlled. The package is usually plastic.

Ceramic gold capped EPROMs and gold legged EPROMs fall into the new category.

Depending on age of a plastic IC with gold legs, it could go into a higher CPU class. As always, post your concerns to get a better answer on what's what.

EDIT* Medical imagery units, scanners, printers, cameras , scientific equipment, and stuff like capturing and inspection tools, mostly carry the CCDs IC or BBDs; which are the glass display ICs with gold inlays. I was lucky to find some of mine in OLD T.V.s and some very particular monitors.

What I would like to distinguish is if a ceramic EPROM with a gold inlay window, can class with or is also, a ceramic gold inlay IC.

Both ICs have windows, both can have gold inlays.