MEDLINE and Embase are two different biomedical databases. MEDLINE is published by the National Library of Medicine in the USA. Embase is published by Elsevier.
But while they are two separate database, all of the journals available in MEDLINE can also be found in Embase. MEDLINE contains more than 22 million records from 5,600 journals, whereas Embase has over 29 million records from 8,500 journals.
Even though everything in MEDLINE can be found in Embase, each database indexes its content in a different way. This means the same search strategy can give different results when used to search MEDLINE or Embase.
This means it is wise to search both databases to ensure you’re finding all relevant results for your search (or use a database search platform that normalizes the data of all the databases it provides accesses to, providing consistent search results between databases).