If both bikes are for the same price and for the same purpose, the hardtail will be lighter. Even for the same price, you could be comparing a light XC full suspension to a downhill hardtail, and probably then, the hardtail would be heavier. But if you woul be comparing two bikes for around the same price built for the same purpose, the hardtail would be lighter.
Full suspensions are not for posers, or actually, any bike could be for a poser, it just depends on what you're looking for. Good full suspension bikes are not cheap, so I wouldn't consider any cheap FS a good option. It just depend on your budget.