Jeff Garcia, the game designer of Zpocalypse said
Our miniatures are 35-40mm high which is right on par with the scale of Last night on earth miniatures.
Which apparently refers to the total height of the miniatures, lowest point to highest point, base included.
The Zombicide miniatures are 28mm "Heroic" scale, which means 28mm from the base of the foot to the eye level with a bit more added because of the heroic.
And thanks to another user here is a picture comparing LNoE figures (same size as Zpocalypse) with Hasslefree miniatures (true 28mm, so a bit smaller than Zombicide).
This means they should have roughly the same scale. If it is an exact match I can not say, but it should be close enough to not cause problems.