Yes, there literally thousands upon thousands of different kinds of strains. Ever since someone first discovered how to cross strain in their own home, the strains are endless.

There are Sativa strains. They grow skinny leaves, tall and lanky, and will give you an up/speedy high. All head high with sativa. Hits you like a ton of bricks.

Then there are indica strains. They grow fat leaves, short and bushier plants. That will give you a couchlock/narcotic high. Body stone, sleepy time weed.

Then there are the countless numbers of strains that are crosses of sativa and indica. That gives you a mix of the two kinds.

Haze is really well known for it's potent, head smoke, 100% sativa I believe. Hard to find 100% sativas as they produce potent as fuckin hell buds.. That is just the name of it, but is more potent than most common strains.

Hydro is just a name of the method they used to grow the pot. Hydro is grown without the use of soil. It is grown using the pressure of water. I'm not 100% sure on that though, I'm not a hydro grower, all I know is that it is grown using water.

I could go on forever with strains. But there are thousands of them, all produce different effects.

Check out www.erowid.com they have TONS of info on marijuana and its effects. Here are a few examples of diffenent kinds of herb:

White Widow
Purple Power
Indian Haze
Lowryder
Panama Red
Power Plant
Big Blue
Strawberry Cough
Bubblegum

Those are names of actual strains you can buy(seeds). All are different in their own way.