the difference between 24 and 16 is dramatic.
But not in the usual way. In terms of listening to A/B comparisons...you may or may not be able to tell the difference. If you have seasoned ears you may be able to distinguish a difference in quality.
But for a recording engineer 24bit recording gives you a dramatic improvement in headroom and dynamic range.
What this means for you is that the same amount of resolution you got at 0db with 16bit, you can get at what...-8 - -12db (or so) at 24bit.
Granted, a lot of people are under the guise that louder is better and want to record everything at 0db all of the time.
But if you consider the fact that you can get great sounding audio resolution and still have 10db of headroom to spare - it opens up a lot of doors. Not only do you not have to be so anal about watching the clip meter (like drums for example)...you can just back off the gain a little, give the track some room to breathe while still capturing it with good resolution and make life easier on yourself. But you also get the opprutunity to deal with really quiet passages and loud passages with great dynamic range with the softer passages still sounding very detailed.
Anyways, yes there is a big difference.