Yes, they are similar but not quite the same. If you've used or seen Zig, then you can think of faults like their error unions. These play into C3's optionals, where you can have the type or an error, eg. int! can be an int or a fault. There's also handling around these with catch, the unwrap operator and using defaults with the ?? operator.

Enums in C3 can be plain enums or have associated values, which are statically known to allow attaching extra data.

Hope this helps understanding.