Whats the difference????and which one is better?????.....then what manufacturer should  I be looking at????

thanks

Cast is when the metal is poured into a mold. Forged receivers are machined from a single piece of metal. Forged is clearly and without question stronger. Cast receivers are pretty tough themselves. I have only heard of three or four cases of AR recievers breaking, but the times I have, have all been cast receivers. See the comparrison chart by Troy tacked on top of this forum to see what manufacturers use which method to make their receivers.

on the same basis what do milled and stamped mean?

We have the same debate with M14 recievers.  Modern metal casting techniques have vastly improved.  The one milled from a forged block will be stronger but the cast is definetly not one to shake a stick at.  
The most recent problems i have seen were with uppers and not lowers found on Oly Arms plinkers.

The "milled vs stamped" means exactly what it says. The differenc between the two in my experience is mostly a matter of asthetics. The stamped reciever on my mac 90 looks like $hit. The finish on most of the milled ak's I've seen look alot better. And as for "cast vs forged", save your money and get a forged reciever. It's not about looks, you wouldent want to be the unlucky one and get a bad casting and have your gun blow up on you.

Agreed, cast is pretty tough, and it will be quite tough for just about anything but hard use. However, the two reports that I have noticed on AR15.com of receivers breaking have both been cast. One guy had a cast Oly lower that was completely shattered upon being accidentaly rolled over by an automobile. The other was a cheap(!) ASA forged lower that broke after 2 (maybe it was 3) shots.

I had seen a pic of an out-of-battery kaboom (high primer?) and naturally, a severly damaged rifle.  And the guy said, see, it was a cast lower and it is all messed up.  Well, truth be known, a forged would have been just as damaged.

I have heard of a few cast lowers cracking due to a casting flaw.  But I am sure any mfg would replace such a lower.

Olympic Arms HAD some MACHINING problems with their cast lowers, holes not drilled correctly, as I understand it.  But it was not due to the fact it was cast.  They corrected the problem, and their current cast lowers are fine.

I think all of the Essential Arms lowers were cast, I know all the ones I have seen were.  And no one I have talked to has had any problem with them.  They were cast by Ruger (no not a rumor), who really have investment casting for firearms down pat.   BTW, Essential made most of their lowers (and matching uppers) with the gray moly finish like the old original M16's.  They had both A1 and A2 uppers available.

However, if any of you feel the urge to replace your cast lowers with forged, I would be glad to accept the old cast lowers and see they are disposed of properly.