The OBD-II protocol (SAE J1979) has a couple of PID's that relate to engine load:
+------+-----+---------------------------------+
| Mode | PID | Description |
+------+-----+---------------------------------+
| 01 | 04 | Calculated engine load value |
+------+-----+---------------------------------+
| 01 | 43 | Absolute engine load value |
+------+-----+---------------------------------+
I can see that calculated engine load is expected to be a number between 0 and 100%, while absolute load ranges between 0 and 25,700%.
Conceptually, what is the difference between these two fields?