Patch vs PatchCreation

[paradigmphantox]

When using PatchCreation in my wxs file, I get a MSP file that works exactly as I expect it to. When using Patch in my wxs, it never works unless the original MSI file is right next to the MSP file (or potentially in the same location I originally ran it from, I haven't checked this). My question is why does PatchCreation generate an MSP that knows to look in the %windir%\installers cache, but Patch does not? The original msi exists in the cache, I have checked. The Patch style msp simply doesn't use it.