притяжательный падеж и родительный падеж
(1)What is the difference between притяжательный падеж and родительный падеж?
I know that притяжательный падеж only be used for people.

(2)I learn from grammar book that it should be consistent with noun in gender,number,case.
дедов карандаш дедова книга дедово письмо дедовы собаки
с дедовом карандашом читать дедову книгу из дедового письма к дедовым собакам
Am I right?

Question

притяжательный падеж и родительный падеж
(1)What is the difference between притяжательный падеж and  родительный падеж?
    I know that  притяжательный падеж only be used  for people.

(2)I learn from grammar book that it should be consistent with noun in gender,number,case.
     дедов карандаш     дедова книга    дедово письмо    дедовы собаки
     с дедовом карандашом    читать дедову книгу    из дедового письма    к дедовым собакам
Am I right?

Answer

1) The possessive case indicates that one noun belongs to another noun or somehow associates with it. It's the most commonly used form of genitive case, but not the only one. The nouns can refer to people or any other objects.

2) The word "дедов" in "дедов карандаш/дедова книга" etc is an adjective and not a noun in possessive form. Adjectives correspond with nouns in gender and number. The possessive form would be "карандаш деда", "книга деда" etc

Answer

compare - дедОВА книга( the related word is in  female gender )   and книга деда ( genitive case ) 
ДедOВ костюм ( male gender) 
ДедОВЫ книги ( both genders in plural )
no difference in meaning they are just different grammar structures
in colloquial speech possessive case is preferable on my opinion

Answer

Thank you! Alexander^_^

Answer

What is the difference between
1) дедова книга
and 
2) книга деда?
When you use  the first case you note not just a physical belonging/legal rights of the book, but you note also a mental/soul "relation".
For ex, if grandfather will give a book as a present to grandmother it will be  книга бабушки but will probably remain дедова книга.