What does Samsung Ultra mean?

Could you please clarify for me what exactly is meant by the term 'Samsung Ultra'? Is it referring to a specific model of smartphone, a premium line of products, or perhaps a marketing term used by Samsung to designate their top-of-the-line devices? I'm curious to know more about what sets these 'Ultra' products apart from their standard offerings and what kind of features or specifications they typically possess. Thank you for your help in shedding some light on this.