File Type is basically synonymous with the term File Format. Both describe the way and manner in which different information is stored on your computer. The media information inside a file is encoded in a particular way, depending on the file type. This information is given to the device to tell how the file in question can be opened.
There are different ways to find out which type of file you are dealing with. One is the file extension that differs from the file type itself. The other is the metadata information of the file which can be stored either inside the file (e.g. in the header) or externally (e.g. in a new file or the file’s mime type).