* Canine breeds: They are both types of dogs, belonging to the same species (Canis lupus familiaris).
* Domesticated: Both breeds were bred by humans for specific purposes (Chihuahuas for companionship and Saint Bernards for rescue).
* Loyal companions: They are both known for their loyalty and affection towards their owners.
* Can be trained: Both breeds can be trained, although the methods and expectations may vary based on size and temperament.
They also both have a wide range of personality traits, some of which may overlap, but ultimately, each individual dog will have its own unique personality.