First of all, let's clarify. When people say 'vert' they mean 'park'. I can't tell you how many times I've seen people refuse to step on a mini-ramp and say "nah, I don't skate vert" (These people obviously have never experienced the sensation of skating a mini-ramp or the joy of being hugged by their fathers. I don't care. It just means more mini-ramp for me). Vert is different. That's what real men skate, but I don't think anyone really expects to hear someone respond with "yeah, I skate vert" these days. So essentially, they are really asking "do you skate street spots or skateparks?" However, as skate parks are more frequently being modeled after natural street spots, you might start questioning if nailing tricks down one of these spots (whether an actual street spot or a replica spot at your park) defines 'skating street' at all.
What do you imagine when you hear the term street skating? I guarantee your mind goes straight to anything like this. Or like this. (These are random examples. I'm not picking out anyone specifically. They're both really great skaters). But let me flip the coin on you. One time someone made the comment to me when I was skating a park, "yeah, but can you skate street." And I was thinking to myself, "does he honestly think I can manual a box and not manual a curb?" Is that how we designate the difference between the two?
So, just because your friend films you doing tricks at some spot downtown (hypothetical example) doesn't mean you "skate street." It just means you are ambitious enough to still go out of the way to find a spot to session when you probably have a park to skate with similar obstacles conveniently located in one enclosed location so you can link together those same tricks on different obstacles without stopping (which isn't a bad thing, everyone needs a change of scenery, I understand). But just skating spots is not "skating street."
When you watch a video part, and see someone nailing out trick-after-trick, you have to consider that they actually planned out what they're doing; that they're not unaware of what obstacle they're approaching and what they intend to do on it. This kind of skating is not natural, its programmed; and it's the opposite of what comes to my mind when I think of street skating.
So, when does the "street skating" come in? Street skating is what happens after this when you just keep going; it's what you do in between sessioning different spots (If you drive to them, you're doing it wrong); street skating is what comes naturally. It is directionless. It's not about making it from point A to point B, it's about how you get there. There are no boundaries, and the only limits to the creative manner you go about doing this are the ones you place on yourself.
Street skating is not something that can be contained, no matter how hard you try. And if you try to contain a street skater, he will always find a way to break free.
Street skating is skateboarding's best kept secret and no matter how hard contests like the Street League and the X-games try to capture the essence of street skating, they are doomed to fail because they are taking everything natural out of it and turning it into a competition to be judged.
I think skaters have been misinterpreting street skating as the idea of the obstacles we limit ourselves to skating instead of looking at it as a mindset. Street skating is how we express ourselves as skaters and whether you are an aggressive individual, a laid-back individual, etc., your style only becomes apparent when you are skating naturally. Think about the way you would approach obstacles if you were put in an unfamiliar setting with your skateboard; how creative would your street skating outlook allow you to be?
To this day, I can't say I've ever seen a skateboarding segment that captures the essence of street skating better than this segment from Mike Vallely's Drive. And even though its obvious from the different camera angles and changing environments that this is happening through multiple takes, they do a great job making it seem like this was one consistent roll through the streets, pushing through obstacles he passes along the way and then continuing to push onward without stopping or having any real direction.