What type of words and sentence structures are used by the playwright?

In Rabbit Hole by David Lindsay-Abaire, Becca is a grieving housewife dealing with the death of her young son Danny. Becca's grief is aggravated by her sister's pregnancy. Her way of dealing with her grief is to essentially erase traces of Danny's memory from the home she shares with her husband Howie, who deals with the loss through obsessive watching of home videos. Becca creates a relationship with Jason, the 17-year-old boy who accidentally hit Danny with his car, the accident that led to Danny's death.
Word choice is called diction, while sentence structure is called syntax.
Throughout the play, Lindsay-Abaire uses conversational diction. This means that the dialogue is written in a way that average people speak. This lends the play its realistic feeling in its representations of grief and healing.
The syntax throughout the play is varied. Some of the characters speak in fragments or partial sentences, another realistic feature of the writing. At certain points in the play, however, a character will have a lengthy monologue that includes compound-complex sentences and even a few run-ons and comma splices. Once again, the syntactical structure in the play establishes verisimilitude and reinforces the authenticity of the plot and its characters.