Your understanding is reasonably correct, although there are a couple of wrinkles to be aware of.
1) The focal length equivalents are a bit of a problem, because the aspect ratios of the negatives/slides differ so much. A comparison between 2 1/4 x 1 5/8 vs. 4 x 5 would take that concern out of the question;
2) To measure the similarities or differences accurately, you need to go so far as to actually print the negatives (or project the slides). And the viewing distance can factor in as well; and
3) The tiny sensor on the digicam will involve you in a further set of complexities - the Bayer array on the sensor, and the equivalent array on the video monitor you use for display. If you don't use a video monitor to display the results, then you get into real concerns about print size if the digicam doesn't have a particularly high resolution sensor.