The difference means little in Madden because you cannot accurately build a one-gap or a two-gap scheme. Madden doesn't have real, authentic gap assignments and gap control schemes.
So if you want a Fairbanks-Bullough 34 were you two-gap, you can't really assure that your players will attack the LOS in such a way that they attract double teams. You can do this for one player--the player you're controlling--by aligning him in the gap between two lineman, but you cannot reasonably assure that your non-controlled players will two-gap. And even when you manually align your player, there's not guarantee that you'll draw a double.
If you want a Phillips 34 where you one-gap, you'll get much closer to that in Madden. My experience by default is that all defenses in Madden are one-gap defenses, with the odd exception of the occasional double team inside.
What I try to do to work with what the game will allow is get 34 end types like Shaughnessy, who are low-70s speed, high 80s strength, and mid 80s block shed. Then I go for one run stopping OLB (LOLB) who has high-60s to low-70s ZCV and one pass rushing OLB (ROLB) who I can play standup in the regular looks or down in the predator look. This is the closes you can get to the Niners' Haley @ the elephant position and Keena Turner on the other side.