No, not necessarily "smaller than MP3" as there is only so much information that you can compress/remove from audio before it sounds bad. VBR MP3 and VBR OGG Vorbis at the same target bitrate are going to be essentially the same size (duh, same bitrate). However, OGG Vorbis generally sounds just as good or better than MP3 at comparative lower bitrates. For example, if you have a 128 kb/s MP3 stream and a 128 kb/s OGG Vorbis stream, there sizes are going to be the same but the OGG Vorbis stream may sound a little better.
At high bitrates, there really is no difference to the "perceived sound". Usually a properly ripped MP3 at VBR 192 kb/s is going to sound just as good as the original. The same goes for OGG Vorbis. However, at 96 kb/s, OGG Vorbis is going to sound better than MP3 at that same bitrate. This is all my own opinion as well as the opinion of others.
The other obvious difference is that the MP3 algorithm/encoding/decoding process is not patent free. It is not that one is open source or the other is not. LAME is an "open source" MP3 encoder. It is not the source, it is the algorithm involved.
OGG Vorbis is a patent free algorithm/encoding/decoding etc. The MP3 algorithm is patented by Fraunhoefer ( http://www.iis.fraunhofer.de/amm/techinf/layer3/
). OGG Vorbis is not patented and actively developed by Xiph ( xiph.org ).
The primary purpose of the DATA statement is to give names to constants; instead of referring to pi as 3.141592653589793 at every appearance, the variable PI can be given that value with a DATA statement and used instead of the longer form of the constant. This also simplifies modifying the program, should the value of pi change.
-- FORTRAN manual for Xerox Computers