1. Ideas
The collective list of distinct ideas or questions your writing will set out to explain or answer.
2. Organization
How you have organized your story. The table of contents and chapters are some ways of organizing the story or writing. "flashbacks" in films is another way of organizing an idea.
3. The voice
The voice is the way a story is being told: is it being told from the writers perspective, or is it told from the perspective of one of the characters or is it told as a "dialogue" and interaction between the characters.
Another way voice is being explained is how a writers "personality" or way of writing and his/her beliefs show up in the writing indirectly through style.
4. word choice
How smartly, beautifully, plainly, or however which suits the author the words are employed to convey meaning.
There are certain writers where this is taken to the utmost art form such as the plays of "Shakespear" a truly remarkable achievement.
5. Sentence fluency
This is an extension of how words are crafted into sentences.
6. Conventions
It is about rules and punctuation and grammar.
For example a "haiku" has an exact format and convention and so does a "Sonnet"