Malaikah (Angels) & Jinns (Invisible Beings)
Devils Among Jinn & Humans
First we need to understand what is defined as a "devil" in Islam. Devil is used for a shaytaan or a satan, which is not a reference to the main satan, the evil jinn who misguided Adam and Eve (alaihim us salaam). In fact, any jinn that is evil and attempts to misguide or harm, in any way, is referred to as a devil. The Arabic word shayateen (plural of shaytaan) can be defined in English as "a group of devils". The term shayateen is generally used by Muslims to refer to the devils among the jinn on earth. Islam teaches us that just like humans have good and bad among them so too does jinn kind. However the ones that collaborate with satan and his followers are the evil ones for whom we use the term shayateen. Another very important thing is the application of the term shayateen is not limited to the devils among the jinn but in fact even humans who are evil and devilish in their habits and nature are included in this term. This is something made clear for us in the Quran and prophetic teachings: (Al Quran 6:112) In the same way We assigned to each prophet an enemy, evil humans and evil jinn. They suggest alluring words to one another in order to deceive. - The famous 20th century Muslim scholar Muhammad Asad (formerly Leopold Weis) in his famous commentary Message of the Quran quotes a prophetic hadith recorded by Imam Tabari that supports this fact about shayateen: the Prophet ﷺ was asked, “Are there satans (shayateen) from among men?” - And he replied, “Yes, and they are more evil than the satans (shayateen) from among the invisible beings (al-jinn).”
Asad explains that in a wider sense, shaytaan is used in the Quran to describe the satanic (exceedingly evil) propensities including all impulses which run counter to reason, truth and morality, in man's own soul and those in the spiritual world (jinns). Such as in the following verse, Allah ﷻ brings our attention to the attitude of hypocrites who, under the influence of their satanic impulses, pretend to be with the believers: (Al Quran 2:14) they assert, "We believe"; but when they find themselves alone with their evil impulses (shayateen), they say, "Verily, we are with you; we were only mocking!" - By following such evil propensities of their own souls these jinns and humans have become like devils.
 Surah Al Anaam (Chapter 6 of the Quran) - Asad 1980