The two planes are parallel since their normal vectors are proportional. The distance between the planes is given by: \[ \text{Distance} = \frac{|d_2 - d_1|}{\sqrt{A^2 + B^2 + C^2}}. \] Here, $A = 2, B = 3, C = 4, d_1 = 4, d_2 = 12/2 = 6$: \[ \text{Distance} = \frac{|6 - 4|}{\sqrt{2^2 + 3^2 + 4^2}} = \frac{2}{\sqrt{29}}. \]