It can be confusing to understand what PubMed is in comparison to Medline, PubMed Central, and even MedlinePlus.
PubMed is the National Library of Medicine's open-access database, encompassing Medline,a health information clearinghouse of articles from the National Library of Medicine, plus articles deposited by authors and publishers as part of National Institutes of Health funding requirements.
Here are some quick explanations.
MedlinePlus is an online health information resource for patients and their families and friends. It is a service of the National Library of Medicine (NLM), the world's largest medical library, and a part of the National Institutes of Health (NIH).