Wordnik defines 'apostrophe' as
"The direct address of an absent or imaginary person or of a personified abstraction, especially as a digression in the course of a speech or composition."
In Ch.23 of Charles Dickens' "Barnaby Rudge" Mr. Chester remarks,
"Ah Ned, Ned, if you would but form your mind by such precepts, we should have but one common feeling on every subject that could possibly arise between us!'
This apostrophe was addressed, like the rest of his remarks, to empty air: for Edward was not present."
Similarly, Wordsworth's sonnet "Milton" which begins, "Milton!thou shouldst be living at this hour" is another famous example of apostrophe.
Wordnik defines 'personification' as,
"A figure of speech in which inanimate objects or abstractions are endowed with human qualities or are represented as possessing human form."
Emily Dickinson's poem "The Train" which begins,"I like to see it lap the miles/ And lick the valleys up" is a fine example of 'personification.'
The difference between 'apostrophe' and 'personification' is that in an apostrophe the person referred to has to be absent [both Edward and Milton are absent], where as in personification it is not necessarily so. Moreover, in an apostrophe persons are merely referred to, where as in personification inanimate objects become endowed with human qualities.