Displacement and Brush Lighting Differences

I'm experiencing some strange lighting when using blend textures and brushes with the same base vtf's. Basically I cannot figure out why it's doing this:

http://cloud.steampowered.com/ugc/595841084682247742/6E679F27B479EB2D8822201610479CE957C0AE80/ Dark area is blend texture and lighter area is the same base vtf from the blend on a brush.

I've tried several combinations of blend textures and even custom textures, editing vmt's from WorldVertex lighting to LightmapGeneric and vice versa etc. and nothing has changed this issue. I'm really just interested in the cause of it at this point, nothing I've been able to find on google has been helpful (maybe I'm just not searching with the right keywords? If I knew the cause I could probably fix it). Anyone have any ideas? Is there some other combination of textures I should be using to counteract this? Sorry to first post with a request for assistance. Compile log shows no errors in vbsp, vvis or vrad. Thanks in advance, this is really a great community and I've enjoyed lurking thus far.

Indeed, making them all displacements did fix everything. Thank you for the quick responses. I wanted to avoid that for selfish reasons but I suppose there's no other choice. Just out of curiosity, why would displacements be lit differently if both a displacement and a brush shared the same VMT which dictates the shader?