Content Controls vs. Forms

Hello,
Does anyone know what’s the difference between using forms (.docxf and .oform) and using content controls in a regular .docx document? Which one should I use?

Thank you.

Edit: Also what’s the difference between adding an image via content controls and adding it using Insert → Image?

Hello,

You can find a description of the oform format and form specs here:

Forms are similar to content controls but they have more advanced field properties and customization options. The API methods of interacting with content controls are also different.
Content control methods are described here:

Form methods description hasn’t been published yet, but we are working on it.

The difference is that these are two different objects and each has its own set of properties.