What's the difference between: "I had been working for ABC for 5 years" and "I worked in ABC company for 5 years". I feel that both are correct but cannot figure out the differences.
The first sentence is complete in itself grammatically but needs a context of previous time or circumstance for completeness of meaning. For examples: “When I was promoted, I had been working ...”; “by the time war started, I had been working ...”.
The second statement is complete grammatically and in meaning. It states a fact that is true regardless of when it became true.