but I am trying to understand if making a game with an engine like Unity or Unreal is much faster than making a game without it.

if (and only if) the engine is suited to the needs of the game in question. engines are typically designed with specific categories of games in mind, such as FPS (unity), open world FPS (unreal), 2d games (gamemaker), etc. when used for games other than the types they were designed for, they can often become a liability rather than an asset.