The text under an IMDb title lists some of the movie’s characteristics: Certificate (rating), runtime, genre, and release date.
Certificate is IMDb-speak for a movie’s rating. In addition, if you scroll down to the bottom of the Storyline section of a typical movie’s listing (arbitrarily chosen), you will see its articulated MPAA rating along with a link to view its corresponding rating in other countries (please also see IMDb ratings of other countries).
So why have “Passed”, “Accepted”, or nothing? The familiar MPAA ratings (G, PG, etc) were not around for the selections you are questioning.
The Motion Picture Production Code, dated March 31, 1930, (aka The Hayes Code) was intended to be a set of rules to govern American filmmaking. This extract describing the code indicates that there was essentially only one rating: Approved. Its absence would mean not approved:
Films were not rated for different ages by the Production Code Administration. They were either approved by the Code for release or not, and the major studios would not release a film without the Code’s seal of approval. In the 1950s a few filmmakers and distributors started to defy the code (especially with foreign imports), and by the 1960s many of the code’s restrictions were loosened if a film’s advertising carried a notice recommending it for mature audiences. [Emphasis mine]
But the Code did not prove to be effective. This extract from Filmmaker IQ describes it pretty well and what happened next:
In March 31, 1930, the MPPDA issued a statement of policy called the The Motion Picture Production Code (also known as the Hays Code). It set up a small jury to review films for content, Understaffed and headed by ineffectual but mostly uninterested board members, the Hays Code was still without teeth and largely mocked by industry insiders.
That changed when the American Bishops of the Roman Catholic Church organized The Legion of Decency and in 1934 with the support of Protestant and Jewish Organizations began calling for boycotts of films deemed unacceptable.
This was the dollar that broke the camel’s back – The Hollywood studios, still reeling from the losses of 1933 due in large part to the delayed effects of the Great Depression, were forced to act.
So in 1934, financial and religious pressure started to make these ratings relevant. In my estimation, this may be the difference between the terms “Passed” and “Approved” as used by IMDb. Again, this is only a guess on my part. But it does seem clear that “Approved” refers directly to the Code.
So how does my theory play out? I more or less randomly chose five movies from the years 1933, 1934, and 1935. Here is what I observed. Please note that Tomorrow at Seven is from 1933, and Roaring City is from 1951.
Some movie selections from 1933 seem to indicate the prevalence of “Passed”:
Some movie selections from 1934 seem to indicate transition (1 apparently not rated):
Some movie selections from 1935 seem to indicate the prevalence of “Approved” (1 Not Rated):
The question example of the unrated film shows that it’s from Denmark. I inspected a number of films from Denmark and noticed that none of them are rated (no rating or “Unrated” or “Not Rated”). I don’t know exactly what this means, but it appears to be common for films from Denmark -- even though there are IMDb equivalent ratings listed for Denmark.