How is the polarized and non polarized LED different ?

[abdulbadii]

How is the polarized and non polarized led structurally different ?
What's the logical explanation on the difference between both types in electrical principals or with respect to semiconductor construction.

 

[jpanhalt]

This report describes the differences (https://www.laserfocusworld.com/art...des-student-develops-first-polarized-led.html ). Interesting find.