I own a 2008 make Samsung A550 LCD tv. It was a popular model and it was released with S3( Samsung panel). The one I purchased came with an au optronics panel(identified by serial and batch number) which is considered as a step below in quality but quite un-discernable unless viewed side by side. Towards the end of tv lifecycle, Samsung supplied with a chi-mei panel which is again one step below au optronics. Companies routinely do this to cut costs as part of six sigma kind of quality programs. The objective is to reduce costs and increase profitability without being very obvious to the customer. Manufacturers have this standard disclaimer that specifications are subject to change based on availability etc... This is just one example that I closely followed.
As of today the Tv still works perfectly. on the other hand, I have a TCL/ Iffalcon tv that has panel failure within 6 months of purchase.