Refactonng is a practice that is an integral part of TDD and is applied both to tests and to code wntten to satisfy those tests.

ATDD is a black-box test design technique that is applicable exclusively at acceptance test level.

BDD is a developer practice where business stakeholders are not usually involved as the tests are directly written at unit/component test level.

ATDD is the practice of running the automated acceptance tests as part of a continuous integration process.