The Hierarchy of Foreignness was a classification system of humans and other species designed by Valentine Wiggin in her "Letter to the Framlings" as Demosthenes, for classifying how "alien" an individual was relative to a subject.
It was organized in four tiers, from least alien to most:
Utlänning means "foreigner" in Swedish.
A främling was defined as a stranger recognized as human, but from a different planet than a subject.
Främling means "stranger" in Swedish.
Ramen were defined as strangers recognized as "human", but of another sentient species entirely. The term was only ever used to refer to the entire species as a whole rather than an individual member.
Ramen means "the frame" or "the framework" in Swedish.
Varelse were defined as true aliens; they may or may not be sentient beings, but are so foreign that no meaningful communication is possible with the subject.
Varelse means "creature" in Swedish.
Application to species
Due to their seemingly genocidal intentions in the three Formic Wars, the Formics were initially considered to be varelse. Their near-xenocide at the hands of Ender Wiggin was celebrated for at least a half-century before public opinion began to change.
The writing of the short novel The Hive Queen showed that the Formics, once they realized that humans were sentient, deeply regretted their actions in the First and Second Formic Wars and decided not to send another colonization fleet to Earth. Their inability to communicate with the humans led to their utter destruction in the Third Invasion. This simple book slowly began to change public opinion, as they began to see the Formics as tragic creatures and see Ender Wiggin as a heinous mass-murderer, the Xenocide.
By the time the Hierarchy of Foreignness was designed, humanity began to refer to the Formics as ramen. However, many were still fearful of the thought that the Formics were still in existence, and when their civilization was re-founded on Lusitania, the human citizens who saw the Formics became terrified.
The first encounters humanity had with the Lusitania-native Pequeninos were peaceful, leading the furry aliens to be deemed as ramen. However, this was disputed after the Pequeninos killed two humans, Pipo Figueira and later Libo Figueira, while attempting to bring them into the "Third Life" stage in the Pequenino life cycle. The Xenologers and Xenobiologists were afraid to ask the Pequeninos about the motives behind the apparent murders, and as a result began to see them as truly alien, the varelse.
However, when it was explained to the humans that the Pequeninos were trying to honor Pipo and Libo by bringing them into the Third Life, they realized that the Pequeninos were not varelse, but simply were unaware that humans could not enter the Third Life. From this point on, Pequeninos were seen as ramen to the inhabitants of Lusitania, but the outside galaxy had no knowledge of this explanation.
Although Humans were the designers and users of the Hierarchy of Foreignness classification system, they themselves were subject to it. Even though the majority of the human galaxy did not question the concept that humans were ramen, after evaluating their attitude towards the Descoladores' existence and the near-xenocide of the Formics, several humans on an exploration team from Lusitania questioned whether humans were ramen or varelse. 
- "He's varelse then, or worse — djur, the dire beast, that comes in the night with slavering jaws."
- — Speaker for the Dead, page 36
The term Djur was mentioned by Andrew Wiggin in conjunction with the rest of the Hierarchy of Foreignness, but was never mentioned again.
However, what can be inferred from his description of the djur is that they are non-sentient beings, capable of independent thought and action, but their mode of communication can not relay any meaningful information to the subject because the djur itself lacks the capacity for rational thought and self-awareness.
Djur means "animal" in Swedish.