AFAIK, all iMac 24" displays have an LG.Philips LM240WU2 LCD panel;
the white 24" are LM240WU2-SLA1, the ALU 24" are LM240WU2-SLB1.
Some posters on this forum have reported them to be "H-IPS" but I've
never seen the term "H-IPS" in any LG.Philips sales literature or data
sheets. OTOH, the LG.Philips web site does have some marketing hype
praising the merits of "Super-IPS" -- but with no indication of which
products use that technology.
LK