Why top shows different information for memory usage?

Issue

• Customer tested several nodes with the same configuration and hardware

• There were two different kinds of display for memory information amond those nodes as shown below:

  Mem:  8207788k av, 6674208k used, 1533580k free,       0k shrd,    3124k buff
        3865924k active,            2062944k inactive
  ------------------------------------------------------------------------------
  Mem:  4099796k av, 4081236k used,   18560k free,       0k shrd,  228936k buff
                     2526008k actv,  961568k in_d,   95620k in_c
  Swap:       0k av,       0k used,       0k free               2754252k cached
  

• Customer wants to know why it shows different output even in the same configuration