As others have already said... Those are trout flies to be used mostly in lakes. Many flies cross borders when it comes to what fish will eat. A lot depends on the time of year and the location in question. Coastal trout tend not to be so selective as interior trout in lakes, because coastal lakes are not generally as productive. There are exceptions of course, and that is usually in the Spring when trout lock into feeding on chironomids. Many flies can represent various forms of trout food: leeches, mayfly nymphs, dragonfly nymphs, damselfly nymphs, and other aquatic items. When there is a BIG hatch of some item then trout tend to be selective to that item during the hatch. However, afterwards they go back to feeding on what is available. Cutthroat trout tend to be more opportunistic than rainbow trout, and they are more likely to feed on other small fish.
It really helps to study the various aquatic items that trout feed on, and the various life stages of those items. Surface fishing with flies tends to have a very narrow window from an angler's perspective.
One of the main reasons why a Wooly Bugger (in all its various forms) is so effective and popular is because it can represent any one of a number of items. It also looks alive, and that alone attracts predatory fish.
There are many, many books on the subject and the field is too diverse to explain in just one comment.
Salmon and steelhead flies are an entirely different subject. Although steelhead will sometimes take trout flies, it is better to use flies designed specifically for them... and with bigger, stronger hooks. Salmon and steelhead do not basically "feed" when they hit fresh water, so most of the flies used for them are attractor patterns for reactionary strikes.