It’s common for people to call all insects bugs. However, entomologists reserve the bug name for a specific group of insects that belong to the suborder Heteroptera (order Hemiptera). To emphasize the point, entomologists refer to these heteropteran insects as the true bugs which may imply we consider all other insects to be false bugs but that’s not true.
All "bugs" aren't bad. Entomologists call insects that belong to the suborder Heteroptera (order Hemiptera) the "true bugs" and insects belonging to the hemipteran family Reduviidae are collectively known as “Assassin Bugs.” The family includes over 190 species in North America and they are all meat-eaters. The common name for the family clearly describes how these predatory stealthy hunters make a living.