Speed, interchangeable lenses, larger image sensor size (don’t fall for megapixels marketing), and better control allowing for effects like depth of field.

The nature of the camera.You can manipulate the SLRs like a manual camera.That is a very good thing.

Sensor size makes a big difference. The individual pixels are bigger so more light falls on them making them more sensitive. Quality of the sensor also makes a big difference to image quality.

As I understand it, interchangeable lenses is one major difference. Regardless of how many megapixels you have, you can only suck so much light through the tiny aperture of a compact lens. There is also recovery time between photos. With a compact you go click and then have to wait a couple of seconds before can click again. With an SLR you can put it in rapid fire mode that will take bursts of a couple of pictures a second. This is a major plus for action shots. Since you aren’t burning up real film, it’s ok to take a series of a gazillion shots and throw away all but the one or two perfect moments.

There are some terrific point and shoot pocket cameras out there. I have a Canon S90 that I love. I also have a Canon Rebel XSI with two lenses that I love also. But you can’t compare the two. More megapixels doesn’t necessarily mean better quality—it just means bigger file size. It all depends on what you want to use it for. If you want a camera to fart around with, and be ultraportable, get a small pocket camera. If, however, you want to do serious photography or have good telephoto capability than you’ll need a dslr with interchangable lenses. You can get by with a big zoom, say like the Tamron 18–200 zoom that gives you one for all, but you sacrifice optics.

1) Regardless of the camera, take lots of pictures. If that means using a point and shoot, because it’s easier to carry, then use a point and shoot. Practice, practice, practice.

2) Edit heavily. Only share your high quality images.

3) Ta da! You are a good photographer!

P.S. As @YoBob writes, SLRs do not have the shutter lag of point and shoots. That might be the biggest advantage in my opinion.

My old 3.2 megapixel point and shoot produced hundreds of great shots, but I missed a hundred, too, thanks to shutter lag.

To add to what everyone else has said, because they’re all great answers, from my experience, even though some compact digital cameras have more megapixels than my DSLR, my photos tend to come out much more crisp and sharp. Also, depending on my lens, I can focus on certain objects very nicely (especially good for portraits). The BG will blur leaving the object in focus and the center of attention, and I have not seen any compact digital camera get that same affect. Also, SLRs are much more fun to play around with. They’re not something you want if you just want to snap photos of friends and families, only get one if you really want to get into photography and taking great photos that have some thought put into them. Some people say it is good to have both point and shoot and and SLR, so you have one for on the go fun photos and one for the serious photos.

Single Lens Reflex > digital solid state whatever. More control over more lenses as well.

If you have a DSLR but only use it on automatic setting, does it still make a large difference over a camera like a Cannon Powershot?

@rooeytoo Yes the DSLR has a much better lens. The difference in quality of the image will show up in large format print, usually in areas along the edge and are better for the DSLR.

Even on the automatic setting, the dSLR will still take the picture faster as well. The difference in speed of the auto-focus means the difference between getting that perfect shot or missing it altogether.

There’s a saying that the best camera is the one you have with you.

I personally employ several point-and-shoots as well as a dSLR. For important family portraits or time-sensitive action shots, I make sure I have the dSLR with me. For a day at Six Flags or the water park, where pocket-sized convenience is key, I take a point-and-shoot, especially if I might want a short video, too. And I’ve always got my iPhone.

Photography is, in my opinion, still more art than science. There’s no perfect camera for all situations. You need to think ahead and choose the right tool. I’ve got a point-and-shoot Canon Powershot that does some amazing autocorrection of up-close flash portraits. But the ability to use a bounce flash with my Nikon dSLR makes beautiful photos in otherwise murky indoor shots. And then, beyond that, you likely will want to use some software to perform some post-processing of your pics to further correct and enhance the images.

THank you for the education. GQ and GAs.

@rooeytoo I shoot with a Canon 60D. It works well for me, thing is, I really love cameras and am a purist when it comes down to it. Some things to take into consideration when owning a dSLR is how willing you are to lug around a pretty high tech machine. Not too mention, the lenses it holds can be pretty pricey. So if you want to simply take family photos and just need quick storage moments the Canon Powershot is more than adequate for taking “automatic” style photos. However, if there are some really good Dslr beginner cameras out there that will do the job! Go to the craigslist and search NIKON d40. i started out with that, and its a really versatile, small camera easy to use and everything. Good luck to your photos! :D

Thanks @dreamwolf, I am sort of looking for a new camera and for me lugging around too much stuff is a pain! But I want something more than the little Fuji that I carry in my pocket. I looked at a Nikon the other day (not DSLR), as well as a Canon and one other, I forget the brand. They all had view finders, used rechargeable batteries and had excellent zooms, but the image stabilization on the Nikon was terrible so I think I will go with the Canon. So many great birds around here, I need a good zoom!