I believe both the 205 & 215 BHP engines are twin turbo the earlier 185 and below are single turbos. When the 205 BHP engine came out there where quite a lot of changes over and above the twin turbo.
More information can be found here for the 205
https://www.media.volvocars.com/glob...releases/18756 and for the 215
https://www.media.volvocars.com/glob...releases/37375