What is the difference between "al-jinn," "al-jann," and "al-jannah," based on the variety of ways these words appear in the Quran?

The difference between the aforementioned terms is that: Al-Jinn (الجن) and Al-Jinnah (الجنة): refer to the collective plural of Jinn, who are the counterparts to humans. Al-Jānn (الجان): refers to the singular of Jinn, which is the progenitor of the Jinn whom Allah created from fire (Iblis). It is also applied to a type of light, swift snake. Al-Jinnah (الجنَّة): means a community of Jinn.

They are called Jinn because they are concealed from people. The root word "jann" (جن) in Arabic means to conceal something from the senses.