The current 13.3" screens are 1600p, the original Retina displays were also 1800p on 15". Only the last generation is a little higher and still not 4K like in PCs. Apple itself has always branded "Retina" based on angular resolution and not surface density, so viewing distance makes a huge difference.

No, their 13'' screens have been 2560x1600 (226ppi) since 2012. You are confused because the nomenclature like 1080p refers to vertical resolution while 4k refers to horizontal resolution.

No to what? I know what 1080p/1600p/1800p is. Here's a direct quote from the Macbook Air tech specs:

Retina display: 13.3-inch (diagonal) LED-backlit display with IPS technology; 2560-by-1600 native resolution

If 1600p on 13" is not Retina you need to argue this with Apple instead.

> If 1600p on 13" is not Retina you need to argue this with Apple instead.

It's 226ppi display. Why would it not be a retina display?

1280x720: 720p

1920x1080: 1080p

2560x1440: 1440p

2560x1600: ...

EDIT: if you're going to edit your comment once called out on talking nonsense, at least have the decency to note it.