How to compare values with more or less

I have a dataframe and i want to compare variables in line 3 using if statement with the use of more or less

let's say i want to compare the same values in third column with more or less 0.2

data >
NAME         A      B      C      D
first        3      2      4      5
second       1      2      3      4
third        7      7.1    7.5    6.9
four         2      1      0      5

here a program to compare the exact values

for (i in 1:3) {
  d <- i+1
  for (j in d:4) {
    if(data [3,i] == data [3,j] ){
        print(paste("The columns" , colnames(data[,i]) ,"and " , colnames(data[,i]) , "are equal"))
    }
  }
}

Here it retuns nothings because the program compares the exacte values and me i want to compare that have the same values more or less 0.2

the result i want is

the column A and B are equal  
the column A and D are equal

it's because A(=7) + or - the same as B(7.1) and the same thing for D A(=7) + or - D (6.9)

Thank you