Take a book like 1984 which is PD in Life+50 countries, and let's say it's PD50. Take a book that's out of copyright in the US which is Life+70 and call it PD70. Any PD50 book can be downloaded in any Life+50 country but not in a Life+70. Any PD70 book can be downloaded in any Life+50 or Life+70 country. Some books have copyright status which is not determined by the author's date of death and have to be treated separately.