QUESTION:
What are the differences between the NASA Pathfinder and the Russian probe?       
 
ANSWER from the Internet and JPL Mars Pathfinder documents on January 17, 1997:
The main scientific objectives of the Mars 96 mission was to 
investigate the evolution and contemporary physics of Mars, and to 
make, using various methods, a wide range of comprehensive studies of those 
physical and chemical processes which took place in the past and which 
continue now. The payload of the Mars 96 orbiter included 24 scientific 
instruments to study the Martian surface, the inner structure of the
planet, its atmosphere and its plasma envelope, as well as instruments
for astrophysical studies.  The spacecraft launch was performed in 
November 1996, with the following components on board.
An Orbiter, two Small autonomous stations to be landed on the surface
of Mars, two Penetrators to examine the underlying surface of Mars.

Additional information on the Mars 96 mission  can be found at the 
following URL:  http://www.iki.rssi.ru/mars96/mars96hp.html

With regard to the Mars Pathfinder Mission: 
The mission is primarily an engineering demonstration of key technologies 
and concepts for eventual use in future missions to Mars employing 
scientific landers.  Pathfinder also delivers science instruments to the 
surface of Mars to investigate the structure of the Martian atmosphere, 
surface meteorology, surface geology, form, and structure, and the 
elemental composition of Martian rocks and soil.  In addition, a 
free-ranging surface rover is deployed to conduct technology  experimemts 
and to serve as an instrument deployment mechanism.

Mars Pathfinder Mission Objectives:
1) "Faster, better, and cheaper" with three years for development and
cost under $150 million dollars. 

2) Demonstrate a simple, low-cost system, at fixed price for placing a
science payload on the surface of Mars at 1/15 the Viking price tag. 
Mars Pathfinder plans to perform a number of significant spacecraft
engineering experiments, to demonstrate a low-cost entry, descent, and 
landing system.

3) Demonstrate NASA's commitment to low-cost planetary exploration by 
completing the mission for a total cost of $280 million dollars
including the launch vehicle and mission operations. 

4) Demonstrate the mobility and usefulness of a microrover on the 
surface of Mars. (The roveris designed to determine rover performance in 
the poorly understood Martian terrain so that future rovers will be 
effective in navigating and moving about the surface of Mars.)

For more specific information about the scientific experiments and 
rover visit the following URL on the internet:
http://mpfwww.jpl.nasa.gov/mpf/mission_obj.html