MP4 is a new container format, a container format allows you to combine different multimedia streams into one single file. Multimedia containers are for example the well known AVI, MPEG , Matroska, OGM. MP4 is the global file extension for the official container format defined in the MPEG-4 standard. MP4 is streamable and supports all kinds of multimedia content, multiple audio-, video-, subtitlestreams, pictures, variable-framerates, -bitrates, -samplerates...) and advanced content like 2D and 3D animated graphics, user interactivity, DVD-like menus.
MPEG-4 Part 14 or *.mp4, is a file format (a so called container) specified as a part of the ISO/IEC MPEG-4 international standard. MPEG-4 is designed to deliver DVD quality video (MPEG-2) at lower bitrates rates and smaller file sizes. MPEG-4 is based on the Advanced Audio Coding (AAC) codec, providing much more efficient compression than MP3 with a quality similiar to that of uncompressed CD audio.