Cute pictures 😀 📸
At a glance, the top one (newer) is clearly more susceptible to lower lighting (e.g., smaller aperture, ccd, etc.) than the bottom one--no argument there; however, the reason(s) for that difference can be a series of engineering compromises and tradeoffs.
For example, I can see here may be everything from sensor size to power consumption, especially considering the differences between the '14 and '20 Airs (e.g., Retina screen, bezel size, CPU performance, etc.) yet the latter has equivalent if not greater battery life than the former.
With that in mind, I think a fairer comparison would be in brighter, more direct lighting. ☀️💡
I can share with you that my aging '17 MacBook Pro looks a lot like your top photo in similar lighting but in bright lighting looks excellent for my screencasts and Zoom meetings.