I just want to know what is the diference between pic samples and commercial pics??? (from microchip of course)
Apart from what's been said allready... Samples might (from time to time) come from a bin of chips that couldn't make it at eg. max. temperature limit, but under lab conditions should perform normally.
They won't be real rejects, as that would just throw people off the product, if it showed as bad circuits.
Oh, another difference... Samples are meant for engineers developing stuff that will be sold in large numbers, to further their business with Microchip, not for amateurs who just want freebies.
Commercial chips are for anyone that pays
The reason that many manufacturers stopped shipping samples to several locations (mainly eastern countries) is misuse of the sampling system, so if you really don't wanna pay the (very small) price for a PIC, at least don't go berserk at the samples and ruin it for professionals which it is directed towards - I bet engineers in Poland, Romania etc. are quite P'd off that so many of their nationals ruined their chance of testing out new products when doing R&D for new products.