There is also a differance in "EDGE" lit LED screens & "BACK" lit LED screens.
EDGE -
Has LED lighting around the edge of the screen. This affords better Black/white contrast w/o the color washout effect of backlit screens.
BACKLIT -
Has an LED lighting array directly behind the viewing surface. This affords a better color gamut of colors seen but a narrower range in contrast.
Both have their pros & cons. It really only matters if you're viewing at a distance -> farther-> than the specific screen size would suggest.
That, and the side angle viewing are probably the ones you would most be able to tell any differances about.
I personally prefer "EDGE" lit. Because most viewing materials are encoded in such a way as to be off black, I like the higher contrast range of the edge lit screens. On a pure black screen, the corners will appear brighter (naturally) and some people do not like that non-uniform image on dark scenes. However, this is only eveident while the set is new. After a burn in of say 100 hours.. the screen will become quite uniform on dark scenes.