R Drop Columns of Another Dataframe from Main Dataframe

Question

I have 2 dataframes,

df1 <- data.frame(a = c(1,2,3,4,9), b = c(1,2,3,4,5) , c = c(1,2,3,4,9), d = c(1,2,3,4,5) )

df2 <- data.frame( c = c(1,2,3,4,5) ,a