Let´s see if I have my ideas right. :p

Low poly refers to models low on number of faces -or geometry-
Normally they´re optimized for game engines and such.

High poly refers to models high on faces counts and such, more or less destined to VFX. Much of the detailing itself comes from the geometry and not the texture, which happens to be a major factor when designing lowpoly.

A normal lowpoly character might have 2000-5000 faces.
A normal highpoly character might have up to 60 000 or more. (depending of course in details)

Hope this helps,