If there is a constraint to compare String with Number, standard-drl (MvelConstraint) coerces String to Number so the evaluation will be Number comparison (e.g. 10 > 5). But exec-model coerces Number to String so the evaluation will be String comparison (e.g. "10" < "5").
Note that we need to use Object or Map to test this because simple comparison String vs Number causes a compilation error.