You can use the anti-join function from dplyr.
library(dplyr)
DF1 <- data.frame(Name = c("B", "C", "A", "E", "D"), value = 1:5)
DF1
Name value
1 B 1
2 C 2
3 A 3
4 E 4
5 D 5
DF2 <- data.frame(Name = c("D", "E", "B", "A"), value = 4:1)
DF2
Name value
1 D 4
2 E 3
3 B 2
4 A 1
Missing <- anti_join(DF1, DF2, by = "Name")
Missing
Name value
1 C 2