Two languages exist in a community and each language is used in specif, mutually used contexts

H and L are used in different contexts, but they can sometimes overlap slightly.
It is very important to use each variety depending on the context.

H is regarded as superior to L.
If H is not considered superior, it is considered more beautiful.
Sometimes, the superiority of H is connected with religion.

Large body of written litterature in H. Produced a long time in the past, or in a community where H serves as standard language.

L is acquired by children as their L1.
H is only taught in school or in other formal educative scenarios.

H is studied in all the levels: grammar rules, syntaxis, etc.
The ortography is well stablished.
In contrast, L has few or none studies.

Diglossia persists at least several centuries.
The communicative tensions that occur in a diglossic situation, may be solved by using intermediate forms of the language.

There are many differences between the grammar of H and L.
There are many categories in H's grammar; whereas, in L there are none.
H has an inflectional system of nouns and verbs.

H and L share many words, with variations.
However, there are only words in H for more technical and professional activities; and, there are words onlhy in L for more homely objects and activities.

H and L share a single phonological system: L is basis and H is subsystem.
Certain items identified as purely H, are replaced with L fonemes.