Stylistic devices are inherent to a language and can be found at its every level, while lingual expressive resources are models creating and intensifying expressiveness.

There is no difference, they are the same

Lingual expressive resources are based on inherent connotation, while stylistic devices can generate expressive units devoid of connotation

Lingual expressive resources are inherent to a language and can be found at its every level, while stylistic devices are models creating and intensifying expressive units.