Difference between ResolveAll and Enumerable.

ResolveAll

Historically Unity did not natively support resolving enumerable. It supported resolving arrays of dependencies but only if these where registered with name. Consider this example:

RegisterType(typeof(IService), typeof(Service));
RegisterType(typeof(IService), typeof(Service),  "Name-1");
RegisterType(typeof(IService), typeof(Service1), "Name-2");
RegisterType(typeof(IService), typeof(Service1), "Name-3");
RegisterType(typeof(IService), typeof(Service1), "Name-4");

When calling ResolveAll<IService> (Resolve<IService[]>) Unity would only return 4 items. These with 'Name-x'.

IEnumerable

Above behavior does not work in all the cases so support for IEnumerable<> has been added. As opposed to ResolveAll resolving Resolve<IEnumerable<SomeType>>() will return all registrations satisfying IServece. So in example above it will return all 5 objects.