PubMed is a biomedical literature database which contains the abstracts of publications in the database.
PubMed Central is a full text repository, which contains the full text of publications in the database.
Publications that are archived in PubMed Central may be found when searching PubMed. In PubMed, the abstract of the publication is available and searchable. The same publication in PubMed Central contains the full text article and the full text is searchable.
For further details on the differences, see the National Library of Medicine Fact Sheet that follows:
* Notice the icon "PMC Full text" to the right. This will link to the full text of the publication in PubMed Central, as in the screenshot to the right. The full text for articles not in PubMed Central will display a U of A blue icon. (see Database Tools & Tips tab for more full text information)