A 318i(s) has a different rear suspension. Cosmetically it has a different interior.
Depends what you mean by a better deal.
Many of us like the ride of a 318ti. A 328 has more torque and will get you to 0-60 quicker. I have never pushed a 328 so I don't know how it handles. My guess is it handles easier but not as much fun to drive. I am biased. I have the best of both worlds. A 2.8 in a ti.
While a Toyota is a fine car it is just a car. It is transportation. I think most of us hear enjoy the ride of a BMW.