The concept of an "adult" feed is flawed from the get-go. There is just feed. Lots of difference target audiences intended by the the feed companies.
Starter? That is high in protein for chicks primarily. It comes in medicated and non-medicated formulas. Non medicated chick starter is a good feed for anyone wanting to feed a higher protein feed, such as during times of moulting.
Grower? Grower is often a medium level (15%) protein feed suitable to fed to any bird, any time.
Layer? Layer is similar to Grower except that it is targeted for laying birds and LAYING BIRDS ONLY. Why? because it is laced with a high calcium amounts that only a laying bird needs and can use. Non laying birds, or any age, should not have a long fed diet of Layer as they do not need the calcium levels that are mixed into it. Such high levels can be potentially harmful to non-laying birds.
Raiser or All Flock? As the names suggest, it is similar to Grower, but usually has a higher protein (20%) and this feed is also suitable for all birds, all ages.
Finisher? A specialized feed for finishing off broilers intended for processing.
Further, the texture of the feed, ie, crumbles, mash or pellets is simply the texture and a preference of the customer. It tells you nothing about the content of the feed itself.