What is the difference between `Requestdto` and `Service` marked `Attribute`

ServiceStack API Design
1

What is the difference between Requestdto and Service marked Attribute(like Route and [Authenticate] or CustomAttribute), which do you suggest placed on?

2

Anything that’s declarative and part of your Service Contract like [Route] should be on your Request DTO, any Request Filter Attributes like [Authenticate] should be on your Service Implementation to ensure your DTOs only have a reference to ServiceStack.Interfaces

3

OK thank you for help