Hello Owais and good afternoon. To answer your question there is just a slight difference between the two. Both sentences mean the same thing generally and both are in the past tense just different time frames. The first sentence "He was called" is in the past simple tense. It describes an event in the past that can be short or long. The second sentence "He had been called" is in the past perfect continuous tense. It denotes a longer action in the past. It is an action that started in the past before another action in the past for example: "He had been called Charles before he changed his name." The first part of the sentence before the word "before" happened first and the second part of the sentence after the word "before" happened after the first one. Remember they both happened in the past before now. I hope this helps and clarifies things for you.

And then he was called Is past tense aswell in that particular moment. For example two people asking why the gate man is taking time to come collect his lunch. 1st person: Sarah, did you call the gate man to come collect his lunch? 2nd person(Sarah): yes! He was called by the house help to come collect his lunch.

He had been called Is past tense. For example two people sitting and having an argument on why the gate man opened the gate late for visitors yesterday. 1st person: why wasn’t the gate opened on time yesterday 2nd person: the Gate man *had been called* on time but never came to open the gate.

He had been called suggests he changed his name.

Past simple and past perfect tenses