PBM is a Portable image in black and white. Can be opened with programs: Adobe Photoshop CS, ACD Systems Canvas 15, ACD Systems ACDSee 17, Newera Graphics Converter Pro, Corel PaintShop Pro X6. File contains 1 bit per pixel. PBM is a kind of file format PPM. And can be readable or binary.
GIF is a format for the exchange of images. It is a popular format graphics. Capable of storing compressed data without loss of quality in the format of not more than 256 colors. GIF format was developed in 1987 (GIF87a) by company CompuServe for transferring raster images over networks. In 1989, the format has been modified (GIF89a), have been added support transparency and animation.