what's the difference between AECCAR2 and CHGCAR?

[pengcx]

I want to konw the distribution about total charge (include core and valence electrons) on FFT-grid NGXF, NGYF, NGZF, similar the CHGCAR (the valence distribution on FFT-grid).
Can I use the sum of AECCAR0 and AECCAR2, ie does CHGCAR_sum represents the distribution of total charge on FFT-grid ? I wonder the difference between AECCAR2 and CHGCAR？
Thanks your answer.

[graeme]

Here is a good description: http://cms.mpi.univie.ac.at/vasp-forum/ ... hp?4.12373