library(stringr)

data001=data.frame(v1= c("你好一二r1c1","你好r2c1一二"),v2=c("三四你好r1c2","三r2c2四你好"))

v3=c()
v4=c()

for (row in 1:nrow(data001)) {

  x=Reduce(setdiff, strsplit(c(as.character(data001$v1[row]), as.character(data001$v2[row])), split = ""))
  x=paste(x, collapse = '')
  v3=c(v3,x)
  y=Reduce(setdiff, strsplit(c(as.character(data001$v2[row]), as.character(data001$v1[row])), split = ""))
  y=paste(y, collapse = '')
  v4=c(v4,y)
}

data002=data.frame(data001,v3,v4)
data002

太感谢了！