I just ran into this. What is the difference between EC2 autoscaling groups, Spot Fleets, and EC2 fleets? At one point they had pretty different features which was a problem, because you might very well need a combination of features no single service had. AWS has largely fixed that by adding featurea to each service, but now it isn't clear why you should choose one over the others. At the very least I wish they would have documentation on how to pick which one to use, and maybe focus on one and deprecate the others.