[X/H] (upper) and [X/Fe] (lower) abundance ratios of wide binary stars and their differences between component stars of each wide binary (blue for WB1, green for WB2, and red for WB3). Dotted lines in the Δ[X/Y] plots denote the value of 0.0 and 0.3 dex, and the error bars indicate the 1σ statistical error. The differences in abundance between component stars are similarly small in the [X/H] and [X/Fe] abundance ratios.