Oscar, Kevin De Bruyne, Eden and Thorgan Hazard and Marko Marin have all arrived since the end of last season.
"This year maybe we are slightly different because we have more new young players coming in so there might not be the settled togetherness that we had on the pitch at that side because we had been together a long time but there is an excitement about our team as well and that's probably the main difference," Lampard told chelseafc.com.
"Everyone is trying to impress, and you never lose that in pre-season, there's not one manager I've met yet who will close the door on any player. We are all playing for our season at this stage trying to show Robbie that we are fit and ready regardless of last year. We have to perform at a high level to stay in the team because of the quality of the squad we have."