I think they just have different philosophies and for the most part are playing to their strengths and qualities of their personnel.
Liverpool are the only team that seem to be trying to play a brand of football that doesn't suit the players they have. Trying to outscore your opponents in every match requires a striker that will bang in 30+ goals a season - they don't have such a player.
I think they can really turn Firmino into a 20+ goals a season striker if they play well from the back. They score most of their goals when one of the front three picks the ball from their own half and takes it all the way to the goal. They need to get their defense sorted out first.