What is diff between AAM, Recurring entries, Sample doccument?

Account Assignment Model:

A reference for document entry that provides default values for posting business transactions. An account assignment model can contain any number of G/L account items and can be changed or supplemented at any time. In contrast to sample documents, the G/L account items for account assignment models may be incomplete.

Recurring Entries:

A periodically recurring posting made by the recurring entry program on the basis of recurring entry original documents.

The procedure is comparable with a standing order by which banks are authorized to debit rent payments, payment contributions or loan repayments.

Sample Documents:

Special type of reference document. Data from this document is used to create default entries on the accounting document entry screen.

Unlike an accounting document, a sample document does not update transaction figures but merely serves as a data source for an accounting document.