Comparing Soil Moisture Tension and Soil Moisture Content
Because Soil Moisture Content is very dependent on soil type there is no easy way to compare it to Soil Moisture Tension without heading off to the laboratory. In general, you are better off not trying to compare the two.
If you really want to know - for a specific sample of soil you can use the HYPROP to determine the retention curve (or water holding characteristics) of that particular soil sample.
This curve relates the soil moisture tension of the soil to its water content, and is important for describing water storage in soil and water availability to plants.
An example of how different the curves for different soil types can be is shown below. A plant growing in a 'typical' sand with a 20% moisture content would be perfectly happy, 10kPa is nice and wet. In any of the other soil types shown, the soil moisture tension at 20% moisture content is well over 100kPa, many plants would have keeled over and died long ago from lack of moisture.