PubMed is primarily used to search MEDLINE. MEDLINE is a relatively selective database, indexing over 30 million journal articles in 5,200 biomedical journals.
Google Scholar (GS) has broader coverage. It can be used to find meeting abstracts and other publication types, not just journal articles. A much larger number of journals can be found in GS than in MEDLINE, as well as a much broader range of disciplines, not just biomedical. GS is useful for supplementing your PubMed search with a broader, interdisciplinary search.
The links below provide more detail on the coverage of each database.
Generally, you can use the same approach to searching in Google Scholar as in Google; for example, the following search would retrieve articles about the spiritual needs of critically ill children:
critically ill children spiritual needs
Here's an example of a longer, more complex search:
child|children|infant|pediatric|neonatal|newborn|newborn|pre-natal "belief in god"|chaplain|"faith in god"|existential|meditation|pastoral|prayer|religion|religious|spiritual|spirituality "critical care"|"critical illness"|"intensive care"|"life support"|nicu||picu|"serious illness"
Google Scholar searches are limited to the first 256 characters (including spaces). You can use | instead of OR to reduce the number of characters you need to use.
Search Google Scholar for articles about RSV in New York City. Try using Boolean operators, phrase search, and truncation.