Is a Mini 14 not as accurate as a AR?
No, not even close.
The late 1980's/1990's mini's seem to be the worst accuracy-wise, at least if reports from the Internet are to be believed. I just know that my 1989-ish, 188-series Ranch Rifle shot a
best ever group of 5.5" at 100 yards, from a benchrest and rear bag. To get that group, I experimented with two different scopes (+ irons), premium and match ammo in various weights from 40 to 69 grains, and 3 different stocks. It was absolutely reliable but wouldn't shoot well. Mine may have been worse than average, though.
It is said that the newer mini's are a bit more accurate, and I have no doubt they are. But IMO the only Mini's that can truly match typical AR-15 accuracy are the $1000+ Target models with the adjustable barrel weight, IMO. The relatively thin cantilevered barrel, heavy reciprocating mass, and somewhat overpowered gas system work against the mini relative to the AR.
The one I am talking about looks like this but with a Bushnell scope and a bigger clear plastic clip. Is this a Ranch Mini 14?
Yes, that appears to be a Ranch Rifle with an aftermarket Butler Creek folding stock (stock retails for about $80 these days). It should say Ranch model on the top of the receiver behind the rear sight, but the fold-down rear sight and the scope bases in front of and behind the ejection port in the photo are clear indicators of the Ranch Rifle. This rifle came from the factory with scope rings, BTW, so make sure you get them, if you choose to buy it.