There are two types of marijuana regardless of the strains. I suppose you can say three but I will hit that soon. Indica and Sativa.
Indica gives that heavy, lazy feeling that relaxes you. It helps you focus a bit more because you are more relaxed. This is good for me when I am working on a project because I have a touch of ADD or ADHD and it's easy for me to lose focus. Another example is seeing my cousin install a car stereo. Usually, he's very talkative but when high and working, you can't stop him til it's done! A lot of strains tend to be heavy indica.
Sativa gives those psychedelic effects but it's not as strong as most people might fear. It's very light and it more or less enhances the moment than anything. This is what makes people find mundane things incredibly hilarious! Sometimes, you may even see flashes of color and images. Don't worry, you are still in your right mind and you won't have the urge to play superman at all!
The "sort of" third is basically the cross between the two. For example, some strains may be 70/30 Indica or even 60/40 Sativa depending on the dominance of the strains. It's very scientific when you get down to it if you understand biology and so on.
Potency
Arizona will most likely be the first kind of weed most people would be able to try especially coming from the city. This is the weakest and cheapest strain of marijuana available. It's grown mainly in Mexico with their dry, arid land. So, the yield will never be as potent as other strains. They also grow quite a lot of marijuana so it's very cheap and easy to get. Usually, your neighborhood dealer will have this. It's good to start out on but it gets annoying after a while. Haze is another "hood" favorite. It's stronger than Arizona but it ain't the best. Other stronger strains that I've tried include Super Silver Haze, White Widow, Grapefruit, Mango, OG Kush, Jack Herer (The Emperpor Wears No Clothes), Hempstar, Sugarbear, BC Big Bud, Chase and I can't remember the others. Some of these are cross strains. Basically, that's just the child of two different strains. For example, my most recent "partaking" included a cross between OG Kush and Grapefruit from a private grower which has no official name yet! It reminded me a lot of Hempstar because it was high in THC and it was FUNKY!
Here's a little story for you to let you know the potency of these strains. I had smoked half a blunt of Hempstar. My boy was coming through so I set up a little gift package for him. The rest of the blunt and enough on the side for him to roll one when he gets home. Before we smoked, we hit up the movies. He was holding the "package" in his coat pocket. About half-hour into the movie, I started to smell it. I asked my boy if he had it out and he said no, it was in his inside coat pocket. Well damn, maybe it's just me. Who could smell it through all of that insulation. Five minutes later, he says that he could smell it too. It ain't my imagination. Fifteen minutes later, a woman two seats away from my boy, three from me, speaking as loudly as any Harlem hoodrat could in a movie theater blurts out that it smells like someone is smoking weed. I just started laughing out loud. My boy apologized and just said that's how potent it is. You can smell that shit that far away. At least, she didn't get stupid about it outside of being a typical loudmouth. Anyway, we get back to my other boy's crib and they hit the half-blunt. These dudes eyes closed right up and I was just watching and laughing at them.
Neither Arizona nor Haze will do that. That's how you know you have quality.