The S13 200SX is a 1.8l turbo, CA18DET, ~170bhp. The S14/S14a/S15 is a 2.0 turbo, SR20DET, ~200bhp.
Insurance group 16/17 for the S13/S14/S14a, as the majority are official UK cars, sold via Nissan UK dealerships. The S15 is import-only - and as such, has a much higher insurance premium.