Batch priming question?

So why is it when you bottle prime you add the sugar straight to the bottle but when you batch prime you boil your sugar in water first? What would happen if you just put the sugar straight into the bottleing bucket?

And what is better to use for priming Table sugar, corn surgar or DME?
I currently use table sugar and was wondering if I would get a better brew from something else?

Thanks

I boil about a cup of water with about 5oz of corn sugar, cool it to room temp, then put it into the bottling bucket. Then I rack the beer from the carboy into the bucket, which mixes it in well enough and bottle it as normal. Works great...

If I had to put sugar by hand in 54 bottles, I'd quit.

I boil water and depending on the style of beer, use the corn sugar, dark brown sugar, light brown and combos of the browns plus molassass.

Then as I start to fill my bottling bucket a little goes in the first quarter of the bucket, some more in the second quarter and the last in the third part. Then before I bottle, I gently stir the beer for a couple seconds or so.

I understand how to batch prime and yes it is easier then bottle priming. My question is why do we boil the sugar in water for batch priming but we don't have to for bottle priming?

If you just dumped the sugar straight into your bottling bucket, it's not going to dissolve very well or mix very thoroughly into the beer, so you'll wind up with unevenly carbonated bottles. So, the sugar has to be dissolved into something that will easily mix in with the beer.

Now, sugar doesn't dissolve very well into cold water. Also, water (especially tap water) tends to have a lot of air in it. Boiling the water makes the sugar dissolve easily into it AND it also drives out that air and oxygen, so you won't risk oxidizing your beer when you introduce the priming sugar.

Also there's that whole sanitizing thing, but that's not 100% necessary as you can tell since you don't really sanitize the sugar you use when bottle priming.