Chinese cash mint differences?

Can someone tell me in historical terms, what was the difference between the "Boo-yuwan" and "boo-ciowan" mints.  

From what I can tell, they were two different issuing authorities in Peking, but is there anyone who has their finger on the (long-dead) pulse of Chinese Imperial coinage that can tell me the Cliff-notes version of why it was that way?

Were the two types of currency used for different purposes (for instance, were the Board of Works cash coins used to pay laborers or soldiers, whereas the other was used for commercial distribution?) or was this just a bureaucratic (or "mandarin", in the adjective sense) oddity?

Just bureaucratic. Different treasuries, different provinces and different boards.

It's similar to how UK has different banks issuing banknotes.

Exactly.

So you can have a poorly-issued Sinkiang coin that's circulated in Szechuan.