Working and usage of lightning:recordForm

A lightning:recordForm component enables you to quickly create forms to add, view, or update a record. Using this component to create record forms is easier than building forms manually with lightning:recordEditForm and lightning:recordViewForm.

The objectApiName attribute is always required, and the recordId is required unless you’re creating a record.This component doesn’t support all Salesforce standard objects. For example, the Event and Task objects are not supported.

The component accepts a mode value that determines the user interaction allowed for the form. The value for mode can be one of the following:

Edit:- Creates an editable form to add a record or update an existing one. When updating an existing record, specify the recordId.

View:- Creates a form to display a record that the user can also edit. The record fields each have an edit button. View mode is the default, and as such, can be omitted.

Readonly:- Creates a form to display a record without enabling edits. The form doesn’t display any buttons.

Edit mode:

Output:

View mode:

Output:

Notice that you can still edit the record from the view mode by clicking the edit button at the end of the field.

Readonly mode:

Output:

For more details refers to :  lightning:recordForm

Refer to link to know more about Difference b/w lightning:recordEditform, force:recordData and lightning:recordForm.