  In this paper, we investigate relations or differences among various
conserved quantities which involve the matter Energy Momentum Tensor (EMT) in
general relativity. These charges include the energy with Einstein's pseudo
EMT, the generalized Komar integral, or the ADM energy, all of which can be
derived from Noether's second theorem, as well as an extra conserved charge
recently proposed in general relativity. For detailed analyses, we apply
definitions of these charges to a system of free massive particles. We employ
the post-Newtonian (PN) expansion to make physical interpretations. We find
that the generalized Komar integral is not conserved at the first non-trivial
order in the PN expansion due to non-zero contributions at spatial boundaries,
while the energy with Einstein's pseudo EMT at this order agrees with a total
energy of massive particles with gravitational interactions through the
Newtonian potential, and thus is conserved. In addition, this total energy is
shown to be identical to the ADM energy not only at this order but also all
orders in the PN expansion. We next calculate an extra conserved charge for the
system of massive particles, at all orders in the PN expansion, which turns out
to be a total number of particles. We call it a gravitational charge, since it
is clearly different from the total energy. We finally discuss an implication
from a fact that there exist two conserved quantities, energy and gravitational
charge, in general relativity.
