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Relief (By-Pass) Valve. In a full flow system, all of the oil passes through the filter to reach the engine. If the filter clogs, an alternative route to the engine must be provided for the oil, or the bearings and other internal parts may fail, due to oil starvation. A relief, or by-pass, valve is used to allow unfiltered oil to lubricate the engine. Unfiltered oil is far better than no oil at all. This relief (by-pass) valve is built into the engine block in some cars. Otherwise, the relief (by-pass) valve is a component of the oil filter itself. Under normal conditions, the valve remains closed. When there is sufficient contaminant in the oil filter to reach a preset level of pressure differential to oil flow (around 10-12 PSI in most passenger cars), pressure differential on the relief (by-pass) valve causes it to open. This condition can occur when the oil filter has become clogged or when the weather is cold and the oil is thick and flows slowly.
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for a toyota filter, the by-pass pressure is higher. since there is less filter media, then it can more easily become clogged. however, at 20-psid, you're loosing quite a bit of flowrate once you trigger the bypass valve. w/ the other filter, the valve will open with less pressure differential, but the chances of that happening are diminished since you have more filter media that has to get clogged before it creates enough backpressure to trigger the by-pass valve. with 40% more media, then it would be the equivalent of having a ~11.2 psid by pass on a toyota filter.
to me, the slighty lower number is better - as stated above, unfiltered oil is better than no oil at all. considering how toyota engines will sludge with old oil, then the lower bypass trigger is better in my opinion.