An imlist object is simply a list of images (of class cimg). For convenience, some generic functions are defined that wouldn't work on plain lists, like plot, display and as.data.frame
DEPRECATION NOTE: in v0.30 of imager, the original behaviour of the "imlist" function was to take a list and turn it into an image list. This behaviour has now been changed to make "imlist" be more like "list". If you wish to turn a list into an image list, use as.imlist.