An e-reader's screen technology is the whole point of the device — it's worth understanding what actually makes E-ink different before comparing anything else.
E-ink vs. LCD/OLED
E-ink screens work by physically rearranging tiny charged particles to form an image, then reflecting whatever ambient light is already in the room — much like actual paper. That's why they're comfortable to read in direct sunlight (where a phone or tablet screen would wash out), don't emit the kind of light linked to evening screen-time eye strain, and sip so little power that battery life is measured in weeks, not hours.
The tradeoff is refresh speed: E-ink is genuinely slow to update compared to a phone screen, which is completely fine for turning pages of text but why E-ink devices are a poor fit for browsing the web, watching video, or anything with fast-moving visuals.
Front light vs. no front light
Most modern E-ink readers include a front light — a thin layer of LEDs that illuminates the screen's surface for reading in the dark, without changing how the underlying E-ink technology works. This is different from a phone's backlight, which shines through the screen; a front light shines across it, which is why E-ink readers with a front light still don't strain the eyes the way a backlit screen can. If reading in bed or dim rooms matters to you, this is worth confirming rather than assuming every e-reader has it.
Storage matters more if you listen to audiobooks
For text-only ebooks, even a modest amount of onboard storage holds thousands of books — file sizes are tiny. Storage becomes a real consideration only if the device also plays audiobooks, since audio files are dramatically larger; a device advertised as "audiobook compatible" is worth checking for actual storage capacity if that's how you plan to use it, rather than assuming ebook-level storage is enough.
The one thing people forget
Check whether the e-reader is tied to one company's bookstore ecosystem, or whether it can open books purchased or borrowed elsewhere (including library apps). Some ecosystems make it straightforward to load outside content; others make it deliberately difficult — worth knowing before you build a library on one platform.