What's the difference between past perfect and past participle? Examples are helpful, but an explanation would be better.
Past Perfect is one of English past tenses used to indicate that one of 2 past actions took place before another like in a sentence:
I had written my homework before I went for a walk.
Form had written suggests that one action (writing homework) took place earlier than the other (going for a walk).
Past Participle is one of the verb forms (usually the third form in a table of irregular verbs). It is used in perfect tenses, passive voice, etc.
Past participle of the verb to write is written. It can be used in:
Past Perfect as in the example above,
Passive Voice: This letter was written by John.