Liquid Retina Eye strain

... what are the major differences between Retina and Liquid retina?

• Retina Display (example): MacBook Pro (13-inch, M2, 2022) - Technical Specifications - Apple Support
• Liquid Retina (example): MacBook Pro - Tech Specs - Apple

One significant difference is brightness. The latter is capable of a significantly brighter image. Your concern is obviously subjective, and the fundamental concern is that one display causes discomfort while another one doesn't.

It's probably not worth mentioning but I'll mention it anyway: I observe nearly every other person using Macs (and even iPhones or similar devices for that matter) at brightness levels I would find intolerable. I usually set mine to perhaps one notch above minimum. If I were to use other people's devices at their preferred brightness levels I'd probably get eye strain and headaches too.

Conversely, if I'm using a Mac and someone wants to look at something on it the first thing they do is crank up the brightness.

You may want to check the Displays Settings on that machine.

Your profile says that you have a 13" MacBook Pro. If that is a 13" MacBook Pro with a plain M1 or M2 chip, it has a 13.3" display with a resolution of 2560x1600 pixels. The ideal Displays Settings choice, in terms of text size and of sharpness, would be Retina "like 1280x800" mode. That would produce "perfect" integer scaling with text that has similar size to that on a 27" 2560x1440 pixel monitor.

However, it is quite possible that Apple has set the Default resolution to squeeze in a little more workspace – at the cost of making text smaller and harder to read. In that case, you might want to choose the 1280x800 mode.

If you have a 14" or 16" Apple Silicon MacBook Pro, those MBPs have screens that have higher PPIs than most other Apple Retina displays. If the Default setting on those corresponds to "perfect" integer scaling, it will produce small text. In that case, you might want to move the setting one notch towards Larger Text.

Apple's comparison tool seems to show that

• 13" Apple Silicon MacBook Pros do not have Liquid Retina displays
• 14" and 16" Apple Silicon MacBook Pros do have Liquid Retina displays

So we are looking at screens that have higher PPIs than most Apple Retina displays, screens where integer scaling will result in text that is on the small side. (Moving the "resolution" setting in Displays Settings one notch towards Larger Text may help with that.)

There may also be differences as far as the use of Pulse Width Modulation to control brightness. Some people are very sensitive to PWM. If a display uses it, and the PWM flicker frequency is too low, that can cause eye strain and headaches, even though the person suffering this could stare straight at the screen and not be consciously aware of the flickering.

NotebookCheck.net is one of the places you can go to find out about PWM.

NotebookCheck.net – Apple MacBook Pro 14 2024 review - The M4 Pro and matte display are massive upgrades

They detected PWM flickering, even at 100% brightness, but said that "The frequency of 14880 Hz is quite high, so most users sensitive to PWM should not notice any flickering."