More opportunities if they belong to the side in power.
It also used to make a difference if one side had a lot of ‘businessmen (or women)’ in their ranks and the other side had a lot of ex shop stewards. Scope for corruption on both sides but different scale and type - certainly when it comes to corruption with government contracts like the PPE scandal.
These days both sides are more likely to be filled with Oxbridge graduates who worked a few years for a bank (or hedge fund) before becoming a researcher for a Cabinet Minister or shadow, and then were forced onto a candidate shortlist in time to join the faceless know nothings in Westminster.