Trail levers have servo-wave which changes modulation throughtout the lever pull.....ie-less linear and no modulation.
The Race style levers have no servo-wave, which means the pull is linear, and allows more modulation.
In Layman's terms, more linear modulation equates to what people think are "squishy" brakes. The servo-wave creates a sharper bite point, which gives the feeling of stronger, grabbier brakes.
It's the difference between rider experience and preference.
If you're doing a mix of levers and calipers, NOT all Shimano brakes work together. Look up spec lists on differences in hoses. The banjo fittings and bolts are different. You might get them to bolt up and "work", but in reality, you don't have fluid flowing properly because the holes are lined up properly in fluid channels.
