Mass (m) is the amount of matter that the body has, measured in kilograms (kg) in the SI. Weight (P) is the force of attraction that a planet exerts on the body, meansured in Newton (N). The relationship between them is given by Definition of Weight:
[tex]P=mg~,~where~g=gravity[/tex]
If you notice any mistake in my english, please let me know, because i am not native.