Italian Neo-Realism
arose in the years following World War II: it sought a break from more traditional filmmaking techniques by focusing on "authenticity" rather than entertainment. A decade later, French filmmakers adopted many of their techniques in their practice of the French New Wave. The two movements possess a number of similarities, including a reliance on spontaneity and the use of nonprofessional actors. Despite that, a number of key differences exist between them.
Time Period
The most obvious difference between the two movements (besides the fact that they arose in different countries) is the time in which they arose. The Neo-Realists operated during a comparatively short period of time, between the end of World War II and the early 1950s. The French New Wave arose later, and it was more self-conscious about what it was doing. It developed Neo-Realist ideas in more sophisticated directions, building upon what their predecessors had begun.
Class and Outlook
Italian Neo-Realism arose from a nation which lost World War II, during a period when its people were suffering under extreme poverty. It often focused on working class protagonists, and on problems of the suffering poor. New Wave filmmakers, on the other hand, came from an ultimately victorious country with a more optimistic view of the future. They often belonged to the middle class, and their films often reflected a more carefree lifestyle.
Tone
French New Wave films tended to be more energetic and upbeat than Italian Neo-Realism. They heightened energy levels through conspicuous techniques such as jump cuts and dialogue aware of its own artifice. In so doing, the French New Wave hoped to break the boundaries of the fourth wall: reminding audiences that they were watching a movie instead of rendering the apparatus of filmmaking invisible. Italian Neo-Realism was much grittier and less playful. It worried less about making the audience aware of its own artifice, and often focused on the subjects being filmed rather than the apparatus of film (such as editing equipment) which the French New Wave delighted in toying with.
Hollywood
Both the French New Wave and Italian Neo-Realism sought to defy the conventions of Hollywood by providing new cinematic tropes and ideas. However -- unlike Neo-Realism -- the French New Wave often adopted Hollywood ideas as a means of shaking them up or drawing attention to their conventional status. For example, the movie "Alphaville" features a private eye named Lemmy Caution who had previously appeared a number of more conventional detective movies, but here was subjected to the signature jump cuts and consciously artificial plot structure utilized by the French New Wave.
