It doesn't look in the least like an iso. The only reason for using it is that I can see it in the fading light (and apparently so can the fish). The point is, I'm not "searching" with it; I know where the fish are.
How about this: an attractor is an attractor because of what it is (gaudy in some sense); a searching pattern is searching pattern because of how it's being used at the moment -- to find trout when they're not obviously rising. The former is intrinsic in the fly, it's an attractor just sitting in my fly box; the latter is functional; it doesn't become a searching fly until I tie it on and use it as such.
It's common to see a fly described as "it makes a good searching pattern"; I don't think I've ever seen a fly described as "it makes a good attractor," rather it's described as "it's an attractor."
(In linguistics, it's the difference between "sense" and "referent", but that's probably too few people here would be familiar with those terms to use them to shed light on the distinction I'm making here.)