first, both are colorful... really...
both shares the exact real live story about producing (idols/anime), not some slice-of-life that ended with fanservice story or romance story, but these two are the real story about real life
both shares the effort of being Producer, and how to step up from the very ver beginner
as you should know, iDOLM@STER starts their idoling from beginner idols which is not-so coordinated each other to become Top Idols
same for Shirobako, actually staff here are really beginner and as the series progress, they work harder as hard as they can, until they make a real great anime />
in both, we could learn anything about (idols in iDOLM@STER, and animation in Shirobako)
and, this might not really, but... in both, we have Matsuoka Yoshitsugu's role as a great boy who're talented and nice