Is past perfect the same as past participle?
No it is not. See explanation.
Past participle is a form of a verb like done, written, played etc. It is used in many situations like perfect tenses, passive voice etc.
Past Perfect is a tense used to indicate that from two events in the past one occured before another. For example:
Yesterday evening he had written a letter before he called John.
In this sentence Past Perfect form had written underlines the order of events: writting a letter happened before calling John.
Past Perfect tense is also used in the third conditional sentences.
The past participle is simply a form of a verb, which is used in the construction of perfect and passive tenses. The past perfect tense uses the past participle of a verb and the verb "to have" in the past tense.
For example, the past participle of "eat" is "eaten."
An example of the verb "eat" in the past perfect tense is "He had eaten all of his supper."
"Eaten" is the past participle and is used to form the past perfect, but they are not the same thing.