The main difference is YPA and primary targets. 90/90 has less separation so naturally the QB checks the ball down a lot which also results in a high comp% usually. 10/10 creates more separation and it's possible to have 400 yard passing games with good to elite QBs where the primary receivers are usually WR 1s and 2s. This will more often than not result in a high comp% as well. I have yet to figure out how to completely control comp% with poor and good QBs completing the appropriate amount. Either way though, the OPI/DPI is for separation so that you can get the ball down field. 5YPA is no good for QBs like Andrew Luck but 8-14 is and that's what you should get with 10/10. It's a matter of preference really as 10/10 will generally be higher scoring games than 90/90.
Also if you're interested, Offsides, False Start and Holding can control sacks and the running game. Put all at 99 and your running game will be strong but sacks will be aplenty, reduce FS and Holding and you'll have less sacks but the running game will be worse. So I assume you could just do 99/94/94 and up Run Blocking until it's where you want it.
EDIT: Even though DPI/OPI is for separation, IG will still control the QBs tendency to throw down field but at 90/90 you won't likely be able to throw over the defender so you'll get an INT.