Enlarger lenses and projector lenses are figured to work flat-to-flat. In other words, project an image of a flat negative or transparency onto flat paper or screen. The camera lens is figured to work a 3 dimensional world (objects at different distances) and project their images on flat film or flat digital image sensor. To accomplish, enlarger and projector lenses are generally symmetrical in design. The camera lens is generally un-symmetrical; thus when tasked to project flat-to-flat they display considerable curvature of field. For this reason most camera lenses with large apertures tend to yield substandard results as projector lenses.

Let me add, when stopped down to f/8 or f/11 satisfactory results are likely. The bottom line is, projector lenses with symmetrical figures are preferable. Another point, the visual focus of the enlarging lens and the chemical focus of the paper are different. Enlarger lenses are color-corrected to avoid such inaccuracy.

The macro lens is also figured to operate flat-to-flat, because when working close focus, depth-of-field is very shallow. When doing close-up work with a standard camera lens, higher sharpness is obtained by reversing the lens. This is because the camera lens projects on flat film or digital sensor -- thus the obverse will serve better when the subject is a flat surface.

An enlarger and a projection lens are generally tasked to project an enlarged image. High projection magnifications require a more complex design, especially when projecting color images. In other words, color correction planes for projection tasks are very different as compared to the camera lens task.