Icons can be interpret in two different ways. consistent and different.
Consistent icons are icons that are easily understood by people, which is universial.
For example, simple icons such as app icons.
Example for Consistent icons
Different icons are icons that can be interpret in different ways depending on people, culture, situation, etc.
For example, major company's logo 'Apple' can be used as an actual apple farm.
Example for icons that are not Consistent
(I AM A MAN poster)
This poster consists a lot of meanings, it can be describe in a lot of different aspects based on it's historical time, purposes, and more. It is also used as book title, art, and plays and in film to assert the rights of all people to be treated with dignity.
To make every viewer understand what it is, the icon should be consistent. (universial)
However, icon that are not consistent, includes lots of different meanings.