E-paper is the category for any display that looks kinda like paper. E-ink is a specific technology (by a specific company, yes,) that uses blobs suspended in oil in small capsules that are controlled by magnetic fields.

Pebble uses a Sharp memory LCD, which as the name suggests, is a liquid crystal display. If you categorize pebbles as a "eink watches", then a gameboy is one low-power memory chip away from being an eink handheld gaming console, the display tech is otherwise identical - a transflective lcd.