I'll run through some of the differences...
Your T1i has a 15 megapixel sensor. The 60D has an 18 megapixel sensor. While there's a difference of 3 megapixels, you probably wont notice that so much since most images don't take advantage of all the image data available (e.g. when displaying on the screen or printing, usually the resolution is lower than the native resolution of the camera.) That difference probably wont jump out at you.
The 60D's sensor is a bit better with ISO performance and noise. Your T1i caps out at ISO 3200 but even at 3200 the noise is pretty high (e.g. use only when desperate). I always tried to keep the ISO on the T1i at or below 800. When you get to 1600 or 3200 you have to acknowledge that you will have a lot of image noise and be prepared to deal with it. The 60D goes to ISO 6400 -- but again, that's going to be noisy. I keep it at 1600 or below. But the net net is that you get an extra stop of ISO performance (both in max potential and in what you'd generally accept as usuable (low to moderate noise)). You probably will notice the improved ISO performance because that translates to lower noise at each ISO you normally use as well as letting you get one extra stop of ISO when needed.
The focus system on the two cameras look the same, as you'll see the familiar 9 auto-focus points on the 60D just like your T1i. But on your T1i, only the center point is a cross-type AF point (dual axis focus point that does phase detect AF both horizontally and vertically; it tends to be faster, more accurate, and is difficult to trick into missing focus.) The 8 outer points are all single-axis only. On the 60D all 9 AF points are the better cross-type points. The focus system is a nice advantage.
The pop-up flash on the 60D can work as a "master" to control off-camera speedlites (they must be Canon or compatible speedlites capable of function as off-camera "slave" flashes -- not all flashes support this.) The pop-up flash on the T1i doesn't support working as a master.
The LCD display on the rear of the 60D is hinged. It swings out and flips (it can be made to face forward if you want.)
The 60D has a monochrome LCD display on the top of the camera. In front of that display are several instant access buttons for AF, Drive, ISO, and metering mode (as well as a 5th button which activates the LCD backlight).
The T1i only has one main dial (just behind the shutter button on the top/front corner). The 60D has a control layout more like Canon's pro level bodies. It adds a 2nd large dial on the rear of the camera. They are positioned so that while the front button is controlled by your index finger, the rear dial is controlled (very comfortably btw) by your thumb. When shooting in manual mode, the front dial controls shutter speed and the rear dial controls aperture. When shooting in a semi-auto (Tv, Av, or P) the rear dial controls exposure compensation. I _really_ prefer the dual dial control layout. It provides faster (not to mention more comfortable) control of camera operation.
The 60D is much better at video. It can handle 1920x1080 at 30 frames per second. It also has better control over audio when recording video.
The mode dial has a dedicated setting for 'Bulb' mode (on the T1i you can get to that by adjusting to the longest possible shutter speed) and the mode dial also has a single Custom ("C") mode. You put the camera into a mode you find yourself wanting to swtich to often, then use the menus to register that as your "custom" mode. It remembers everything you set... when you want to return to those settings you just switch to custom mode. It can be a quick way to switch between modes (e.g. if you're shooting sports but want to swtich between AI Servo focus and One Shot focus rapidly depending on whether you're shooting people candids vs. action shots.) I use the mode in astrophotography as a framing and exposure test mode.
Tim Campbell
5D III, 5D IV, 60Da
