asd

awk 'FNR==NR {a[$1] = $2;c[$1] = $1;next;}{b[$1] = $2;c[$1] = $1;} END {printf "TABLE\tREF\tHEAD\tdifference\n"; for(i in c) printf "%s\t%d\t%d\t%d\n", i, a[i], b[i], a[i]-b[i]}' test.txt test1.txt
TABLE	REF	HEAD	difference
viewer	23	2990	-2967
remark	2	240	-238
test	27	0	27
exam	0	200	-200