This is an apples to orange comparo. The FX is a rigid street bike with sporty riding position,the DS is an upright dual-purpose bike with front suspension. The DS will def weight more with the suspension fork,hydro disc brakes,and wider,treaded tires. Assuming the same rider,it will be slower due to the extra weight and drag from the tires. But it will also be more comfortable on bad roads,be better suited to off road,and be a better choice for bad weather(esp snow) riding. Basically,you're choosing a sporty coupe or a crossover SUV.

As for bike weights,manufacturers rarely give them because they're not set in stone. Different size frames will be lighter/heavier,components can change from what's listed,and things like tires have a range they can weigh. If manufacturers did post weights,you can bet there would be cheating like over in the motorcycle world. They'd weigh them without pedals,and prolly also without reflectors and valve stem caps,and would prolly go through a selection of tires to get the lightest pair.