I'm not 100% sure, but I think the corporate versions have longer range because they carry extra fuel tanks which aren't found on commercial versions due to weight issues. The premise is that a corporate version won't be carrying 100 people (or whatever the number is) plus all their baggage.

I know the Legacy, which is the corporate version of the EMB135, has a ventral tank and winglets which isn't found on the airline version.

Maybe that's why the Lineage has a 4000 mile range, but I don't think the airplane was ever designed to be able to carry fuel for that range plus a full passenger load. I'm sure they can build a variant that way but it would be so weight restricted it wouldn't be economically feasible.

But that's just my guess. I'm probably wrong.