Pubmed is an interface used to search Medline, as well as additional biomedical content. Ovid Medline is an interface for searching only Medline content. Pubmed is more user-friendly and allows you to search through more content than Ovid Medline. However, Ovid Medline allows you to perform a more focused/structured search. You will get slightly different results by searching in each database.
In Pubmed, in addition to Medline articles, you will have access to PubMedCentral papers, which are full text articles deposited to promote open access, and articles that are “in process” (with approximately 7 days time lag) that is, prior to being indexed with MeSH terms, and articles submitted by publishers, “ahead of print.” This is why if you search for the same term in Medline and in Pubmed, you may obtain as many as ten thousand more articles in Pubmed.
Here is the link to the National Library of Medicine’s page with a much more complete explanation of how Medline, Pubmed and PubMedCentral are different:
Before you give up on searching Ovid Medline, here is why you may want to use it for certain searches.
All Medline articles have been indexed with assigned MeSH terms. If you have a specific search you are doing you will get the closest, most specific match to your terms by searching in Medline. This is why it is good to perform your search in more than one database.