accessing list.head, deconstruction vs method call

Question

I am trying to learn a bit of Scala and got stuck on a small oddity when as far as I can I can write the same in two supposedly equivalent ways, but one runs and the other does not.

val test_array = Array(1,2,3,4,5,6,7,8,9,10,3,4)
val it = test_array.sliding(2).toList

def iter(lst: List[Array[Int]]): List[Boolean] = lst match {
  case h :: Nil => List(false)
  case h :: tail => tail.map(x => x.sameElements(lst.head)) ++ iter(tail)
}

if(iter(it).contains(true)) ...

and

val test_array = Array(1,2,3,4,5,6,7,8,9,10,3,4)
val it = test_array.sliding(2).toList

def iter(lst: List[Array[Int]]): List[Boolean] = lst match {
  case h :: Nil => List(false)
  case h :: tail => tail.map(x => x.sameElements(h)) ++ iter(tail)
}

if(iter(it).contains(true)) ...

The first example runs, the second throws a noSuchMethodError: scala.collection.immutable.$colon$colon.hd$1()

The only difference is how I access head. In one case I use the deconstruction way and the other I use list.head. Why does one run and the other does not?