Just to compare them and not to weigh them, then you could use a seesaw.
balance
no we use relative mass
It is used to compare masses.
The mass of a proton is 1836 times greater than the mass of an electron.
Compare their weights when they're both in the same gravitational environment ... on the surface of the Earth, for example. Under those conditions, their weights will be directly proportional to their masses.
mass of electron = 1/1836 mass of proton (or neutron)
grams
Comparing density
0.8 kg and 800 g are equivalent masses.
Increase the masses.
Why should you compare activities for applicability