TXT is a file format that contains the text, organized in rows. Text files opposed binaries that contain data that is not intended for interpretation as a text (encoded sound or image). The text file can contain both formatted and unformatted text. Since the very simple text files, they are frequently used for storing data.
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.