Yes .. and it can be a useful difference for each..
I consider cock rings (as a functional description) to be something which doesn't quite fit yet when you're flaccid, and something which generally precludes becoming flaccid again once you're erect.
Of course someone could get a cockring that's either way too small or way too big and fall outside of those effects .. but generally the above is what should be expected.
I find it less than optimal for A.D.S. usage .. and what's actually superior is a two inch (or so) length of silicone sleeve* around the base of the penis, softly constricted by one or two 'hair ties' (the stretchy kind).
By experimenting with tying a knot in the excess size of a hair tie, one can customize a constrictor size that is both 'firm' but also flimsy, allowing it to:
-keep an expanded (almost 'clamped') state of tumescence, even when you would otherwise be flaccid, ..
-stretch enough to not become overly tight during an actual erection, so that the erection can pass..
-and allow for an ongoing circulation of bloodflow (in either a hard
or soft penis state) so there's no adverse occlusion or necrosis.
(*) The form factor for the silicone sleeve, as I do it, is to cut one slice vertically in the length of sleeve (this makes it a roll instead of a tube) and then it can be stretched around the base of the penis until it overlaps itself, .. and the hair-tie holds it together. This lets you make the cushioning sleeve a customized size as well, and since the sleeve itself is also stretchy it's probably contributing to the quality of the constriction instead of just being a passive cushion.
Done right, this is an
extremely useful method for staying in an anti-turtle state. -- For me it causes (approximately) a 110% expansion of girth, a 95% expansion of length, at about a 70% state of 'erection'. Those figures are far beyond any anti-turtle sleeve or a wrap. And it can do this for hours until it becomes an uncomfortable rubbing against the base. Then just remove, massage, and if desired re-apply.
Additional comment: this is like the fifth time I've posted this methodology to various threads. It seems like the concept of being able to anti-turtle in an actively expanded (practically 'clamped') state, .. as a boost to
SRT .. re -active healing .. would catch on. (?) Or at least get a "Hmmm.."
Watch your color and how it feels. If the color looks wrong, or the feeling feels wrong .. it is. Stop immediately and make your next hair ties larger until you get the right mix.
Alt tip - some types of hair ties would rather die fighting than be stretched around and tied into a custom knotted form. If you end up with those, you don't have to fight with them or go buy a different kind .. just get a needle and thread and put a few stitches in the hair tie where you would have otherwise knotted it.