Petr lived on the outside, in his neighborhood in the city, not in hiding, but moving about Prague during the occupation.
St. Vitus Cathedral, Prague, from Charles Bridge
He knew he would be sent to the ghetto at Terezin, a/k/a Theresienstadt at the age of 14, as a Mischling. That was a policy postponement of several years, because he was not a full-blooded Jew, but a Mischling.
See post dated 8/7/07 for "Mischling," the category of mixed Jewish and Aryan, that carried with it some dispensations, but only those of delay - not reprieve.
He lived under a clock ticking, and he knew where he would be sent. And he had a life to live in the meanwhile, out there.
From the diary, his life was in a varied, constantly changing city, with a large population, old buildings, family and friends, Nazis, tradition and history, constant reminders and sights and stimulation of many kinds for a child, including brutal reprisals in news. I do not believe he saw people shot, but the word spread.
Child and adult war diarists. See Europe Road Ways: Themes and Common Threads.
Anne Frank was in another world. Ask what difference do the surroundings make to someone keeping a diary.
Anne Frank and Petr Ginz were in the same war, but Anne had nothing to "do," except look inwards and at a limited area and limited number of people; while Petr was in the midst of city, family, visible and experienced occupation events, all the time. That may well be the cultural view of girls as more verbal, introspective, reflective, and boys out doing. Still, Petr also was introspective, as shown by his art and fiction - if he had been in an attic for several years, his diary may well have been less matter-of-fact.
Here was Anne Frank's world - hidden inside and up a concealed staircase, no movement or sounds allowed during the day:.
Anne Frank house, Amsterdam NL
Imagine the days of Anne Frank: confined, in hiding, on tiptoe, fearful, only one window high up for daylight in her room,and only changing leaves and the branches of a tree across the canal to see. Even that tree is being cut down now. See history1900s.about.com/b/a/256911.htm.
There is the door to her father's office and business, in a narrow row-building warehouse. *The Annex, behind a secret way and up hidden stairs, is behind, and extends at the top. See www.annefrank.com/1_life.htm.
The same few people, little change, day after day. She wrote from the inside, of herself and the few rooms they all occupied. Her prose may soar at times, but how much of that reflects the lack of other stimulation? She could concentrate on her feelings - what else was there to do.
Back to original question: How much of a writing style depends on the enrichment of the surroundings, on distraction and lack of it. Or is style a reflection seriously of gender, with the girls looking inward and the boys figuring out how things work, and the bell-shaped curve on that; or just plain human difference in perspective, regardless of gender or distraction.
Likely: Petr's reporting style, succinct, factual, looks like a shorthand of someone whose days and head were full of daily confronting the uncontrollable. A wry detachment makes sense. A way of controlling at least how and what was recorded. A way to sanity.
Petr Ginz died at Auschwitz, after a period of time at Theresienstadt. Anne Frank died at Bergen-Belsen, after a period of time at Auschwitz.