Compare two tables

What is the easiest way and the fastest way to compare dataframes. Input:

df1 <- data.frame(ID = c(1, 2, 3, 4),
                  A = c(1, 2, 3, NA),
                  B = c(1, 2, NA, NA))
> df1
  ID  A  B
1  1  1  1
2  2  2  2
3  3  3 NA
4  4 NA NA

df2 <- data.frame(ID = c(1, 2, 3, 4),
                  A = c(1, 2, 3, 4),
                  B = c(1, 2, 3, NA))
> df2
  ID A  B
1  1 1  1
2  2 2  2
3  3 3  3
4  4 4 NA

I assume that data frames have the same amount of rows and columns. The output data frame should contain:

1. Column ID with values from df1 or df2 - (doesn't mather if from df1 or df2 because they are the same.
2. In columns A and B shoud be value from df2 if content of cell from df1 is different than in df2, or NA if values are the same.

I can use for and iterate for every row and column but it is not elegant solution. Is it better?

I tried:

result = apply(ifelse(df1[,] == df2[,], NA, df2[,])

but doesn't work.

The output df should look like this:

result <- data.frame(ID = c(1, 2, 3, 4),
                  A = c(NA, NA, NA, 4),
                  B = c(NA, NA, 3, NA)) 

> result
  ID  A  B
1  1 NA NA
2  2 NA NA
3  3 NA  3
4  4  4 NA