Let me try and put this in layman's terms...
Magnetism and gravity are two different forces, based on two different quantities. Magnetism is highly related to electric charge, so I would probably have an easier time explaining it in terms of that. Electric charge and gravity are two forces that behave in remarkably similar ways. They are both inverse square forces, which get weaker with the square of the radius. They are also both related to the product of the quantities of the two objects in question. Mass for gravity, electric charge for the electric force. F = m1m2G/r^2. F = q1q2C/r^2. G and C are two rmarkably similar constants as well. G is negative, however, and C is positive (or vice versa depending on your system) denoting that like masses attract, while like charges repel. In the metric system, mass in measured in kilograms, and charge in coulombs.
For two coulomb particles, the constant is such that the force is much greater than for two neutral kilogram particles. How one relates charge units and gravity units, though is somewhat of a mystery to me as well. Perhaps it is merely because we deal in our everyday lives with quantities of charge that yeild far stronger forces than the quantities of mass involved.
As for magnetism, magnetism is a weird force that is related to the electric force, but is much stranger than that. A similar equation exists for magnetism, B1B2T/r^2, but there is also a complicated relationship between charge, magnetic polarity, and velocity.
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