how to combine two outputs from the awk and some another grep?

 The paste command is your friend:

paste <(cat csim.stats.txt|  grep snap  | cut -d "_" -f 6| cut -d "." -f 1 ) <(cat csim.stats.txt| grep "Type=           5" |  awk '{n+=$4;printf"%s %s\n",$4,n }') >snap2part.txt