What is stronger edt spray or edt splash in mens fragrances?

The cap type of a fragrance bottle will not affect its strength/potency, it is simply a difference in how the fragrance is applied (a spray cap uses a atomiser/mister, whereas a splash cap is simply has a hollow opening).

Overall, a spray cap is far more effective for getting the most out of your fragrance. The liquid is secluded and unexposed within the bottle (enabling longer shelf life), the atomiser delivers the liquid without the use of intermediates (no wasted fragrance left on hands, cotton swabs, etc), and the fragrance distribution of the atomiser is more even and consistent (whereas spreading droplets from a splash cap can be inconsistent).

The only advantages of a splash cap are the ability to apply directly where desired and the less expensive price of the bottle (typically 15% to 25% less). However, with the factor of wasted fragrance mentioned earlier, many still consider the advantage of a splash cap to be unsubstantial.