Раньше comes from "ранний" which means "early", i.e. "раньше" is basically a superlative form.
In other words "раньше" means "recently" or "earlier", while "в прошлом" heavily implies in the [not so recent] past.
Главный переводчик много работал журналистом в прошлом.
"He worked as a journalist a lot in the past", i.e. he's worked many professions since then or he hasn't worked at all for a long time.
Главный переводчик много работал журналистом раньше.
"He's worked a lot as a journalist recently/earlier", i.e. it was his most recent job and now he works as a plumber.