Do it this way:
A<-read.table(text="Word Freq
p 9531
can 2085
/p 2055
get 1183
use 1112",header=T)
B<-read.table(text="Word Freq
p 10
can 2
/p 55",header=T)
A[-which(A$Word %in% B$Word),]
result:
Word Freq
4 get 1183
5 use 1112