As nouns the difference between mastiff and beetle
is that
mastiff is a large breed of dog often confused to be part of a type of large dogs the mastiff is a breed of its own that is sometimes referred to as an "english mastiff" other breeds have mastiff in their informal name such as "french mastiff" for dogue de bordeaux or include mastiff in their breed names; tibetan mastiff or neapolitan mastiff all are different breeds as well as the often confused bullmastiff while
beetle is any of numerous species of insect in the order coleoptera characterized by a pair of hard, shell-like front wings which cover and protect a pair of rear wings when at rest or
beetle can be a type of mallet with a large wooden head, used to drive wedges, beat pavements, etc.
As a verb beetle is
to move away quickly, to scurry away or
beetle can be to loom over; to extend or jut or
beetle can be to beat with a heavy mallet.
As an adjective beetle is
protruding, jutting, overhanging (as in
beetle brows ).