My personal definitions-
Clone- A knife made to look like an identical or near identical version of an existing knife, but without the markings of the real thing, and sometimes with its own distinct brand/markings.
Counterfeit- A knife made to look like an identical or near identical version of another knife, and bearing the markings of the real thing, with the intent of tryingto trick people into believing it's the real thing.
Of course opinions and personal definitions will vary.
In regards to your knife, I found a post here on Bladeforums from 2010 where a member said they purchased a knife just like yours at Walmart (opening hole, no model number or date code).
So maybe it's genuine. Perhaps it was a special run just for Walmart (extra cheap). Either that or the member was mistaken where he bought it, or Walmart was selling counterfeits. It seems strange to me that Buck would sell knives without date codes, but it also surprised me that the Access (with thumbstud and date code) doesn't have a model number on it. So who knows.