Difference between using Custom Content as a Widget or as a Field

Sometimes on our support, we recommend the use of the special Custom Content field, however, there's a small difference between its placement inside your View:

• If it's placed inside the Widget zone of your View, then we'll call it Custom Content Widget;
• If it should be placed inside the "Entries Fields" section, then we'll call it Custom Content Field.

They are both Custom Content, but when adding a Custom Content field, you get access to the field Merge Tags dropdown:

Field Merge Tags won't work inside the Custom Content when using it as a Widget because of the context. Fields are part of the entries zone on the View. Widgets are outside of that zone.