Patterns of Service objects inside the Service layer

Many architecture patterns mention some type of service layer like in DDD, onion architecture, hexagonal, etc...

Recently I noticed that my service layer tends to grow to type of service objects

1. 
   

   Singleton service objects with no constructor.

   
   

   Mailer.send(message)

   
   


2. 
   

   Temporal services with constructors.

   
   

   PersonService.new(user_session).find_all

   
   

Is there any naming or pattern that makes a difference while describing these two types of service objects?

I am noticing some patterns in their use, like the second case being more common when an external service talks to the inner model. However I am curious if some of the architectures mention this in more detail or if there is different naming / related patterns that tend to coexist inside the objects of the service layer.