I believe most chip collectors use the term limited edition for any chip that was made mainly to sell to collectors and tourists rather than to play the game in the casino. Most are 'limited' only because by the time the casino runs out, there's another 'LE' design to order instead [g]. Basically any chip that isn't a 'rack chip' is a 'LE' to most in the hobby.

Note that the back pages in JamesC's reference book are labeled 'Limited Editions', and he puts all but rack chips back there.