Both of these can be included when applying for a job, Pychometric tests can often be required as part of the job application process before being invited to an Assessment centre, they can also feature on the Assessment centre days.
Graduate psychometric tests help to identify your skills, knowledge and personality. They're objective, convenient and strong indicators of job performance - making them very popular with large graduate recruiters.
The majority of psychometric testing is completed online, though some paper questionnaires remain. Most tests are timed, but some can be completed in multiple sittings. Source Prospects
When applying for a job an Assessment Centre is a section of the application process where you will face presentations, group work exercises and psychometric tests.
Assessment centres are designed to challenge your skills, and enables employers to find out more about your personality.