I have both and find in practice I use them quite differently.
Veils: quick and easy to patch up as a vca with up to 4 channels of mixing. To be honest I use it 95% with linear response (I adjust attack via the envelope itself), but it is nice to have the option there. If set to exponential with no cv input you can generate up to two time gain which is usually enough to boost line level to modular level. Likewise you can change to response curve with no cv plugged in which I find gives smooth response if you want to gradually fade a track in manually. Veils is also good to plug modulation in and use the vca to bring the modulation in and out.
Blinds: I find blinds excels at mixing cv sources, which can change a static modulation into a more dynamic or evolving modulation source. Blinds is also good at taking a unipolar cv source and using the 5V offset to create bipolar modulation. I rarely use Blinds as an audio vca because it takes more effort to setup. VCA gain is also maximum of unity gain and sometimes the volume boost is helpful on Veils. As a bonus you can patch Blinds as a ring modulator, this is fun from time to time. I don’t use this much so is nice to not have a dedicated module for that purpose.
hope this helps