What's the difference between "lived", "have lived", "used to live", and "would live"?

Question

What's the differences between the below sentences and which of them is correct or more correct?
It seems that all of them have the same meaning. If it's true, then which of them is more common in daily routine conversation?

1. I lived in Tehran (Iran's Capital) from 1950-1960. (Past Simple).
2. I've lived in Tehran for a decade. (Present Perfect).
3. I used to live in Tehran for a decade. (Past Continuous).

We all know that we can also use “would” to talk about things that happened regularly in the past, but on the other side “would” cannot be used to talk about states in the past. “used to” must be used instead.

But I sometimes hear in movies from native speakers that use like below sentence in their conversation between each others:

4. I would live in Tehran for a decade before I moved to Canada.
   Is it correct to use this structure (NO.4) in our casual conversation?

In the end, which do you suggest to use in the below sentence, “used to” or “lived”?

5. When we were children, we used to live (or lived?) in Tehran. In summer, if the weather was fine, we would all get up early and look around the city.

Answer 1

These sentences all seem correct, but they do not all have the same meaning. Let's go through them one by one.

I lived in Tehran from 1950-1960.

This seems pretty self-explanatory. You lived in Tehran. You lived in Tehran for the years you indicated. If the year is 1961, you aren't in Tehran anymore, unless you indicate it again.

I've lived in Tehran for a decade.

This could have several meanings, but the most likely meaning is this: You moved to Tehran a decade ago. You're still in Tehran. It's been a decade, and you're still there.

I used to live in Tehran for a decade.

You lived in Tehran for a decade. When exactly? Who knows. That time period that you lived there, however, was ten years. You don't live in Tehran anymore, though. This sentence is similar in meaning to the first sentence, it's just not as specific.

I would live in Tehran for a decade before I moved to Canada.

This is an interesting sentence. It sounds like something a first-person narrator in a movie would say. As is mentioned in the comments, it sounds very autobiographical. Can you use it in a casual conversation? Sure. But it doesn't seem like something you say right away; it sounds like something you say as you're telling or concluding a story.

Now, in terms of which one is more common in conversation, it is impossible to say, because the sentences convey different meanings. However, I can probably bet that the fourth one is rarely used in conversation, if at all.

Now, for your fifth sentence, I think it comes down to personal preference. I would most likely say

When we were children, we lived in Tehran...

but that's just my preference.

Answer 2

The first three examples are all correct, however examples 1 and 3 have a different meaning from example 2. Example 4 is also correct but has a very different meaning from the others.

Example 1 and 3 express that in the past someone lived in Tehran and no longer does. Example 2 expresses that he is currently living in Tehran and has for a decade. Between examples 1 and 3, example 1 is considered more correct for formal writing because it does not use unnecessary verbs (i.e. the "used to" can be removed just by changing "live" to past tense).

Example 4 is a proper sentence, but is expressing one's preference for future actions rather than something one has done. In that sentence, the speaker is saying that he would rather live to Tehran for a decade than move to Canada. A more proper wording of the sentence would be "I would rather live in Tehran for a decade than move to Canada," but it works for informal speech as it is worded (without the rather). The implication behind this sentence is that Tehran is an undesirable place to live (at least for the speaker), so the fact that he would rather live there for a decade than move to Canada expresses how he finds Canada even more undesirable than something the listener knows he already finds undesirable. It is essentially saying the speaker dislikes Tehran, but he dislikes Canada even more.

I would word your sentence as follows: "When we were children, we lived in Tehran. In summer, if the weather was fine, we would all get up early and look around the city."