I used to live verses I have lived

Both are past tense.

Ah yes, sorry. I didn't add 'the past' at the end of the present perfect sentence. Apologies.

What's the difference between the two is more what I was asking eh.

Their meaning is the same.

I'm not sure it is or, the function isn't.

Questions about "meaning" of a sentence depend on context of presentation.

Individually, each sentence could mean the same, but juxtaposing them calls for a possible differentiation. In that sense "I have lived in Barcelona" suggests for example that the speaker could be making an authoritative point about experience of the place (... stressing I's experience). A similar contrastive point might be made about "used to" implying "not now".

(Note that many questions on EFL threads generate pages of waffle by not taking into account the context sensitive nature of semantics)

I agree - there is an inferred difference. To me 'I used to live in Barcelona' infers Barcelona was a home for a long period of time - whereas 'I have lived in Barcelona' doesn't infer as long a connection (at least to my interpretation). It's not a grammatical rule just how it sounds to me.

Ooooooh! I like that idea about time! Here's an example of the function...

I have lived in many places - this seems about right to me.

I used to live in many places - this doesn't seem about right to me.

However, context is important in both here.

For example;
I used to live in many places while I was a traveller....
I have lived in many places while I was a traveller.... (That should be 'had')