Pulling stats from here:
Guard Nade
Guard grenade is 45 munis.
Bundle Grenade
Bundle grenade is 45 munis.
Shock Troop Grenade
Shock grenade is either 30 or 35 munis, 30, I think.
(warning: in the topic I pulled these from some people had trouble with the links going to the wrong things for some reason)
There was a thread recently on guard grenades, which had a little comparing with the Pgren bundle grenade. Anyway, the basic difference as far as I can see (please correct me if I've missed something important) is that Guard grenades have half the windup time (.125 as opposed to .25) and 1.5 as opposed to 1.0 'accuracy' in open terrain for some reason. I don't know if that has any effect on things or why there's a discrepancy *just* in open terrain.
When you go over to Shock Nades, the RG 42 has a radius of 4 as opposed to 6, has a near and far range of 1 and 2 as opposed to 1.5 and 3. Windup is .25 like the bundlenade. Otherwise target tables for the three grenades look pretty similar for all real occasions.
So, of the three units, the most AT unit has the best anti-infantry nade (not a big difference in the raw stats from the bundlenade aside from the weird open 'accuracy' difference which looks like a mistake to me, but as it's against smaller squads I'd say it's way better in practice). The most AI unit has far and away the weakest grenade.
So, leading question time. Is this maybe part of the reason Shocks are kind of underused right now (the stat difference definitely explains how underwhelming Shock nades are)? I mean, Guards as a useful multipurpose AT unit will often win an engagement with P-grens through a grenade, whereas shocks as a dedicated AI unit will often lose one after taking a grenade.