b46 vs b48

looking for a 30i car and very confused between differences of b46 and b48. google says b46 is 1.6L 4c single turbo, and b48 is 2.0L 4c twin scroll. however everyone i’ve seen on forums says there’s almost no difference. like hello 0.4L of displacement is a massive difference! looking at a 430i 2018 tmrw but it’s a sulev car. i assume this means b46. however description of the car says 2.0L 4c. someone help me out here