Difference between Kilogram-weight and mass

As long as the body stays on the Earth, it is irrelevant. What the statement really says is $m=$ 700 kg.

A body weights 700kgwt on earth surface.

This statement means that the weight of the body is equal to that of a 700 kg mass. So, you should consider the mass of the body to be 700 kg

One kilogram-weight is the force of gravity felt by a mass of 1 kg. On Earth, $gsimeq 9.8$ so $$1 text{ kg}_w= 1 text{ kg}cdot g=9.8 text{ N}$$

So, to answer your question we have $$700 text{ kg}_w/g=71 text{ kg}$$ where 71 kg is the mass of the object, as such it remains the same in the entire universe.

Now you have to calculate $g_{text{new}}$, the gravitational acceleration on the other planet, recalling that $$g_{text{new}}=Gfrac{M_text{new}}{r^2_text{new}}=gfrac {M_text{new}}{M_text{Earth}}frac{r^2_text{Earth}}{r^2_{text{new}}}$$

Then the desired answer is $$boxed{71text{ kg}cdot g_{text{new}}}$$

The weight of a mass depends on these formulas: see link below.

The mass is a measurement of the amount of stuff like protons, neutrons and electrons. In the two formulas below the mass (m) which is the inertial mass stays the same. On the smaller planet (M) is 1/7 the mass of Earth and (r) is 1/2 the radius of Earth. You can measure the inertial mass on either planet or even in space by placing it on a spring and measuring the oscillation period. Equal masses will always have equal oscillations. [1]: https://i.stack.imgur.com/C4AaF.jpg