What is the difference between "Provisional Application" and "Nonprovisional Application"?

A provisional application shall include a specification as prescribed by 35 USC 112(a) and a drawing as prescribed by 35 USC 113. 35 USC 111(b)(1). However, claims are not required to be included in a provisional application. Id. at (b)(2). Provisional applications may be advantageous in obtaining the filing date because the filing date of a provisional application shall be the date on which a specification, with or without claims, is received in the United States Patent and Trademark Office. Id. at (b)(4). This means even when claims are still under revision, an applicant may file the patent application to secure the filing date. An applicant who decides to initially file a provisional application must file a corresponding nonprovisional application during the 12-month pendency period of the provisional application in order to benefit from the earlier provisional application filing. (See http://www.uspto.gov/patents-getting-started/patent-basics/types-patent-applications/nonprovisional-utility-patent#heading-1.) No provisional patent application will be issued and provisional applications will not undergo the examination. (See http://www.noreklaw.com/provisional_vs_nonprovisional.htm.)
I found the below links useful for figuring out the differences between the two applications.
http://www.uspto.gov/patents-getting-started/patent-basics/types-patent-applications/nonprovisional-utility-patent#heading-1
http://www.noreklaw.com/provisional_vs_nonprovisional.htm