HARM : You need them for "shoot outs." RWR yells at
you, missiles in the air, SHOOT the HARM. (Those over the shoulder
launches bring a tear to my eye....)
JDAM : RWR Naked, you get information from ELINT / SIGINT
/ COMMINT ppl that there's a StraightFlush radar at the mentioned
coordinates. Fly high and fast, and drop the JDAM.
Different weapon, different purpose. Apply them wrongly,
and you have a dead pilot.
Nobody knows what other devious plans the ADA ppl have up their
sleeves in real life, no need to say online discussion.
In USAF terms:
HARM: cued by RWR or other means-- Suppress Enemy Air
Defense-SEAD.
JDAM: cued by Elint/Sigint/Commint by means of VLBI or LBI to
geo-locate the hostile SAM's radar---Destruct Enemy Air
Defense--DEAD
Yankees are evil enough to upgrade the current SEAD
version of HARM to DEAD version of Harm by adopting the
technologies used widely by PGMs.