What do the Red & blue show impacts hitboxes mean?

[Munch]

I've noticed recently after the patch with the awp a month or two ago that a lot of my AWP shots which look like they should hit don't, even though the shot appears to register ( blood splatters on wall, etc). I tested this using show impacts and found that sometimes the shots that didnt register only had the red hitbox highlighted, and the shot will only hit if the blue shot hit.
What does this mean? Do the hitboxes represent client/server side?

[apple]

Red hitboxes means client side. Blue hitbox is server side