[@PolkaDancer]
It's energy.

Lightsabers are presumably "Hardlight" weapons, in that they form a beam of light in a way that makes them hard. That's probably in the way of a super thin beam that blows really brightly. As to how it's possible- it ain't. It's fiction. I doubt we could EVER create a lightsaber.

And blaster 'bullets' are, again, lasers. It takes an energy source and fires a beam of superheat. Real-life lasers are actually relatively-instantaneous beams of heat. That's all a laser is, and that's why lasers burn.