User blog comment:Psogen/12th Squad/@comment-11446176-20141001081132

Afaik while the SRDI is essentially made up of the 12th squad, they're two different things.

The SRDI was just founded by Urahara, and uses members from that group. The 12th has always seemed to be involved with research though, what with two royal guard members seemingly related to the division, but what Urahara did was (to me), just make open it up. Might be possible that non-shinigami are involved too