There are over 6,000 different citation styles! Most of the time, you'll be told which style to use by a journal editor or a professor. The most important part of this is being consistent and being able to follow guidelines. Check out the Virginia Tech Libraries' citation style page for guidelines related to the most frequently used citation styles:
A few examples of these frequently used styles are:
You will need to be able to understand citation types AND citation formats in order to know what you are looking at and how to properly cite the sources in a list of references.
Citation type: BOOK; Citation format: APA
Citation type: JOURNAL ARTICLE; Citation format: APA
Citation type: WEBSITE; Citation format: APA
PLEASE NOTE: There are many, many types of web citations. Find more examples of how to cite web materials at: https://owl.english.purdue.edu/owl/resource/560/10
As read through articles, books, and other resources, and use others lists of references or bibliographies in order to find resources, you'll see a lot of different types of citations (book, journal, website, data etc.) and citation styles (APA, MLA, Chicago etc.)