PDF is a file format developed by Adobe Systems for representing documents in a manner that is separate from the original operating system, application or hardware from where it was originally created. A PDF file can be any length, contain any number of fonts and images and is designed to enable the creation and transfer of printer-ready output.
Each PDF file encapsulates a complete description of a 2D document (and, with the advent of Acrobat 3D, embedded 3D documents) that includes the text, fonts, images and 2D vector graphics that compose the document. They do not encode information that is specific to the application software, hardware, or operating system used to create or view the document.
The LRF file type is a proprietary file type created by Sony for use with Sony branded eBook readers. LRF, along with LRS and LRX made up the now defunct BroadBand eBook or BBeB. The file type was discontinued in 2010 with the Sony eBook store selling in the ePUB format.