Kind of confused on what the constant offset is? and what is the difference between the constant and relative offset is.

Think about you have a cube with dimensions of 2.5*3.5*4.5 unit Relative offset will set the distance for each cube by 2.5(x axis) automatically[relative offset of 1 (if 3, distance is 3*2.5 = 7.5 unit)]. But constant offset the distance is rely on the value you set, if 1 in x axis, the distance from first cube and the next is 1 unit. Hope that helps :)