A lot of people are talking about plasma and such, but from what I understand blaster bolts are not actually plasma bolts. They seem more like charged particle clouds.
A charged particle cloud makes more sense, and fits all the seen examples.
1) Damage: Damage from a blaster bolt is closer to flaying than it is to burning. It is like being hit with a super sand blaster. Every particle in the cloud that hits the target has a decent chance of passing part way into it before hitting another particle, and when it does it would shove whatever particle it hits and agitate other particles, causing a ripple effect until the energy bleeds off enough to stop effecting nearby particles. It would feel like a burn and look like a burn too. It is even possible to explain stun settings with this if you use a more less charged and less dense cloud. With the lower overall charge it is less likely to interact with objects and more likely to pass through. If enough of the cloud breaches the skin and passes by nerves, they are highly likely to agitate them, and if you do this over enough of the body at once it will cause shock.
2) Speed: A charged particle cloud would move at whatever speed it was projected at. Since the cloud is charges, the most likely projection method is using railgun like electromagnetic coils. These can move objects very quickly, but not light speed.
3) Maximum range: Blaster bolts disperse after a certain distance. This is simply the cloud not being able to maintain coherence enough to do effective damage. This especially plays a part in space. A charged particle cloud would be bouncing internally to the cloud, thus causing it to disperse. A laser or slug will continue along its path basically forever.
4) Deflection and redirection: In this case, you are not actually parrying the particles, but bringing the charged field of the lightsaber into line with the charged field of the blast. Same charges = repelled bolt. Same goes for deflection shields. All they are doing is producing a charged field that interacts with the field of the bolt. As the charges interact it would even cause some stress on the generator, thus being able to blast through them with enough power.
So what all this means with slug throwers and blasters:
1) They probably have about the same penetration, just in different ways.
2) A blaster bolt would be as fast as the projector is set to and still maintain the coherency of the clouds. Bullets are as fast as.. well... bullets.
3) Blasters have and bullets both have an effective range in a gravity well, but the bullet likely should have a longer range. Outside a gravity well, the bullet doesn't stop but the bolt stops being effective eventually.
4) Blasters can be parried and redirected. Bullets might be destroyed, depending on material, but could never be redirected.
Chunks of this are a result of reading though wookiepedia as well as some of my own interpretations based on various things said about blaster bolts and how they react to the enviroment.
I just realized that was way longer than I thought it would be.