Im not sure about major differences, But im guessing EXI lacks the following
-Power Steering (These models have an hydraulic power steering that means a big conversation but still shouldnt be more then 10-15k)
-Power Windows (You can source a set from scrap market (bilal gunj etc) It shouldnt be more then 20k bolt on)
-Central locking (you can always get a after market system)
-If the meter cluster is different (that can be changed)
-Rest is same.
The best bet is to consult your mechanic, Major cost is how cheap you get the parts, Conversation labour shouldnt be too much.