CiviCRM Community Forums (archive)

No, they are not. CiviCRM uses it's own DB Layer (PEAR:DB), Forms (QuickForm) Presentation layer (smarty), Access Control, etc. It does not use Drupal's APIs for these things.

However, CiviCRM does include an API that makes it possible to write code to synchronize data with Drupal modules, and includea few module sot do this, E.g., Role sync, and Organic Groups sync. There is also a relatively new CCK field type module that exposes CiviCRM contacts. CiviCRM also provides Views integration.