Cascade filter realization equivalence?
As MattL already mentioned, they are the same block diagrams as Direct Form II (canonical) implementation of a third order (on the FIR side) LCCDE. 

However, the adders in the first block diagram are two input adders, while the the ones in the second block diagram are multiple input adders. Theoretically there is no difference.  

In a popular DSP text, only the former block diagram is displayed, with sum (sigma) symbol replaced with a + sign.