* OHV (Overhead Valve): This was the more common engine. It's generally what people think of when they say "4.0L Ford Explorer engine" from that era.
* SOHC (Single Overhead Camshaft): A less common, but still available, variation of the 4.0L. It offered some minor improvements in performance and efficiency compared to the OHV version.
The differences were primarily in the valve train configuration. Unless you were deeply familiar with engine mechanics or had access to detailed specifications, you wouldn't readily notice the difference between the two just by looking at the engine bay.
