There are two ways to look at the division of literature:
Either you can divide it into poetry and prose. This is a common way of dividing literary types, and is taught to many literature students.
As for subdivisions, there are endless genres and styles. Different poetic forms and conventions, so to list all the subdivisions of poetry and prose here would create an endless list.
Another division of literature is to look at fiction and non-fiction.
This second division of literature is a little more contested, because not all people agree that non-fiction constitutes literature.
In its strictest sense, the term literature applies to works of prose or poetry which are accepted into the 'literary cannon'.
Not a clear definition, I know....
The way I look at it is that the literary cannon comprises the writing of authors who have been recognised for their contribution by institutions like universities and , rather than merely books that are popular with the general public.
An example I really like is the works of Charles Dickens.
In his time, Dickens saw his writing published in common magazines and newspapers. And Victorians saw his tales as curiosity and amusement, rather than serious works of literature.
So, originally, the works of Charles Dickens were not considered literature.
But, over time, he began to gain recognition, and institutes began to study and teach his books, and his work become held in such high regard that he now represents the upper echelons of the literary cannon.