In other words, the FLARE emits electromagnetic radiation, that arrives at the speed of light (8 minutes). Flares themselves (x-rays, uv, microwave) don't usually cause aurora unless they are extremely powerful. They can blind satellites temporarily.
Coronal mass ejection (CME) - actual pieces of the sun, billions of tons of super heated hydrogen and helium are ejected by the flare and travel at close to the speed of light, but take a few days to get here from the Sun. This mass carries a lot more energy, and when it impacts our atmosphere, this is when we the Aurora. This mass is also what can damage satellites... it slows them down by increasing drag, heats them up (drag again) and delivers an electric charge to the hull which can short out sensors / antennas, etc.
For a really good show, and risk of satellite damage, the CME and our magnetosphere (the magnetic shield of the planet) have to have an attractive polarization, and a certain geometry. For example, when you try to force two magnets together, North to North they push away, but if you flip one magnet over so it is North to South, then they attract... same thing happens on a huge scale in the atmosphere. When the polarization lines up, the magnetosphere actually sucks the CME into our atmosphere, rather than deflecting it away.
Once the CME gets sucked in, the energy from that hot hydrogen and helium dumps into our ionosphere (where the ozone protects us). All that energy makes the oxygen and nitrogen glow as it absorbs and dissipates the excess energy. Billions and billions of watts of electrical energy are generated by a strong storm, and that energy can sometimes play havoc with power grids and radio operations on the ground.
