Language is the dress of thought.
Samuel Johnson
Bilingual copy editing involves comparing the target text with the source text contentually and linguistically. Texts are checked for their completeness, correct spelling and grammar and consistent terminology. Close attention is also paid to good style.
Proofreading is the sole review of an already copy-edited translation. The focus here is on typos, punctuation and correct layout. There is no checking with the content in the source text.