Of course, this varies depending on the size of the originals and the size and resolution needs of your output. The moral of the story is - garbage in makes garbage out. Optical resolution is what the scanner can actually resolve in terms of pixels. Interpolated resolutions are simply software guessing at what the extra pixels should be. On our scanner comparison page we only refer to Optical Resolutions.
Bit depth is a measure of how many different colors the scanner can distinguish.
No matter how colorful your original is, you are always limited by the amount of color that the scanner can actually capture. Density range describes how many steps between total white and total black that the scanner can distinguish on a scale from 1 - 4. Higher density ranges will capture more detail in the highlights and shadows. XY Technology is unique because the optical array moves in 2 dimensions. This makes for lower resolutions or more distortion around the edges of the scanning bed.