What is a digraph blend?

I'm not 100% sure and am happy to be corrected, but this is my understanding of it: Blends are combinations of consonants where you can still hear the two separate sounds, eg. br, cr, pl. This seems counterintuitive to me, as 'blend' implies that you mixing something together so that it is indistinguishable, but apparently that's what a blend is. Digraphs are where two letters are used to represent a single sound - sh, th, wh, ch.