A GEOTIFF is a special kind of TIF (of TIFF) file that contains additioinal information about the map projection and registration in addition to the raster image. TIFF is "tagged image format", and initially was developed for scanners.
A geotiff can be displayed by any graphics program that can handle TIFF images, but that program will not have any mapping capabilities, and cannot supply coordinates.
The Geotiff format, like the TIFF format, has a very large number of possible options including compression, tiling, and photographic interpretation. A single file can contain several satellite image bands, which is common with aerial photography and some satellite images. A file can also contain multiple images, but that option does not appear to be very common in GIS applications.
Fields in a typical Geotiff file.
Geotiff is probably the best publicly documented format for raster data, and can be used for imagery, scanned paper maps, and DEMs. With a corrretly created GeoTiff, you only the the TIF file. Many files profess to be Geotiffs, but in fact do not have any tags with the geospatial information. They instead rely on a a TFW world file containing registration information, although the world file does not contact any information about the projection since it was developed in an era when all layers on a map shared the same projection.
Geotiffs in MICRODEM
Last revision 12/30/2017