The difference of Neo Noir to Film Noir is probably that Neo Noir is not necessarily in black and white, neither with low key photography. It is more that the topics and especially the mood of the movies are similar to Film Noir.

Here an example of film noir, the trailer of "Dark Passage" with Humphrey Bogart of 1947

Here an example for Neo Noir, martin Scorseses "Taxi Driver" from 1976