"LABS is just a Toss Bombing Mode where you pull up until the bomb is released to giving it a ballistic path with an upward vector. Just Loft bombing
CMPTR mode is a pseudo CCRP with target preselection upon depressing the release button, to let the computer calculate the release point.
On the A-4 Mod maybe isn´t any difference. Yet. LABS was used first to accomodate the CMPTR mode, but now CMPTR is fully coded so no need of LABS. Maybe on the A-4 was an option for nukes and thats why in the mod is no difference because nukes are not modelled."
In the past: LABS mode was used. That's why there are videos teaching it.
After v2.0: use CMPTR mode