Gauss vs Tesla

I've heard magnetic fields are also measured in gauss.  What's the difference?
Gauss (G) is the unit of measurement for B in the older CGS (centimeter-gram-second) system, whereas tesla (T) is the preferred Système Internationale (SI) term.  For conversion, 1 T equals 10,000 G. Alternatively, 1 G = 0.1 mT.  Because the tesla is a relatively large unit, it is most suitably used to define the strength of the main magnetic field in the center of an MR scanner.  Gauss are sometimes used when describing much smaller fields, such as those associated with gradients, radiofrequency coils, or fringe fields at some distance from the MR scanner. 
References
     IEEE Magnetics Society, "Magnetic Units".  Table of definitions and conversion factors for various magnetic quantities between CGS and SI systems.  
Related Questions 
     We have a 3.0 tesla MR scanner at our hospital.  I know this is a very strong magnet, but what exactly is a tesla?