Layer = more calcium, less protein (16-17%), cheaper in cost.
Flock Raiser/Maker/All Flock = less calcium, more protein, usually in the 18-20% range, and more expensive.
Why it matters. Layer feed is designed for laying chickens. The calcium is needed for the pullets/hens, but is too much for cockerels/roosters for long periods. It's 16% protein because it's what commercial egg producers have figured out is the lowest (cheapest) formulation to feed and still get eggs. If they could get production levels they need on less, believe me, it would be less. Pennies matter at their scale.
All flock/Flock raiser/Maker has the amount of calcium that birds of either sex need, but you have to provide extra on the side for laying pullets/hens (in the form of oyster shells or crushed egg shells, or both), so they get enough to lay eggs with good shells. The layers will instinctively take what they need. The others might sample, but probably won't eat much. This type of feed also has a higher percentage of protein, and is therefore more expensive. A lot of the formulations are good for mixed flocks, and you might want to consider that if you're adding ducks.
I settled on Kalmbach Flock Maker 20%, which I get for about $23/50 pound bag. The other "bells and whistles," ie, non-GMO, organic, soy free, or corn free, are going to add to the cost of any brand of feed.