What Is Their Main Difference?
'Need to' is used when we are using the semi-modal 'need' as a main verb. It expresses requirements. For example:
Talking about Requirements
Requirements are what needs to be done for something else to happen. We use 'need to' to talk about requirements. Have a look:
Talking about Obligations
We use 'have to' to express obligations. Obligations are what must be done. Take a look at the following examples:
To make 'have to' and 'need to,' we follow the pattern below:
- do/did/does + not + have/need to
In the negative form, 'have to' and 'need to' convey the same meaning. They both express that you are not required to do something. For instance:
Are They Interchangeable?
Some obligations are requirements. We might 'have to' do something for something else to happen therefore we can use 'need to' and 'have to' interchangeably. For example:
To make interrogative forms, we follow the pattern illustrated below: