Settings > Form Type
The form type is based on how much information you want to collect on your order form. The Standard order form will collect Billing Address, where the Slim order form will not collect Billing Address.
Click the images below to see larger previews of each form type.
Slim Preview (No Billing Information)
The Standard form type is set to collect the Billing Address at default, but you can also set it to collect a 'Phone Number' and/or 'Shipping Address' just by enabling the toggles that are available in the Form Type settings for the Standard form:
Once you have enabled one or both of these options, and have published your form, the additional information will be required, and the information will be included in the information available in your 'Orders' tab
Here is an example of how your checkout page will look with Shipping Address and Phone Number enabled:
Standard Preview (With Shipping Address & Phone Number enabled)
By default, the 'Shipping Information' entered will automatically populate the 'Billing Information', but there is an option (shown in the picture above) to change the Billing Address, if it happens to differ from the Shipping Address.