Usage of "Had been" and "Used to"

Question

Are this two tenses convenient to use for the same purpose, for the event in the past that began, lasted and finished?

For example:

I used to live in London

I had been living in London

Where is the difference?

Answer 1

Usage of “Had been” and “Used to” Q. Are this two tenses convenient to use for the same purpose, for the event in the past that began, lasted and finished?

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A. Yes, but they are not interchangeable. It is the context & phrasing that make the use of used to acceptable. You will note I have had to write used to .. "be" in my example below. In effect we are using "used to" to form the past tense of "be" which is in effect been.

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Had been - There had been a shop on the street corner since I was a kid. Now it was "Boarded up" and some kids sat in the doorway with plastic bags over their faces.

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used to - There used to "be" a shop on the street corner when I lived here. Now it was "Boarded up" and some kids sat in the doorway with plastic bags over their faces.*

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been; verb; past participle of be Ref CED Been

used; verb; used to shows that a particular thing always happened or was true in the past, especially if it no longer happens or is no longer true: Ref CED used to

Answer 2

According to the Cambridge Dictionary, used to generally means:

done or experienced in the past, but no longer done or experienced

Note the two highlighted words: this makes it perfect for a sentence like yours, which is about something that you did in the past but no longer do.

I used to live in London.

had been is past perfect continuous: we generally use this to describe something that happened before some other event in the past, and we generally specify how long we had been doing it: the following sentence does not specify how long, and there is no other event in your sentence, so it doesn't work in your sentence.

I had been living in London. - incorrect on its own

Note that this sentence would be valid as an answer to a question that specifies an event, for example:

Where were you living before you met your wife?

The following sentence is correct on its own, because it specifies a time interval and an event that it preceded:

I had been living in London for five years when I first met my future wife. - correct