| Feature | Custom Objects | External Objects |
|---|---|---|
| Data is stored in your Salesforce org | Yes | No |
| Read | Yes | Yes |
| Write | Yes | Yes (limited) |
| Tabs, layouts | Yes | Yes |
| Visualforce | Yes | Yes |
| Field-level security | Yes | Yes |
| Sharing | Yes | No |
| REST and SOAP API | Yes | Yes |
| SOQL | Yes | Yes (limited) |
| Search and SOSL | Yes | Yes (pass-through) |
| Formula fields | Yes | Not Yet |
| Workflow, triggers | Yes | Not Yet |
| Reports and analytics | Yes | Not Yet |
| Chatter | Yes | Yes (no field tracking) |