The two Dutchmen go head-to-head in the Premier League for the first time at Old Trafford on Sunday since Slot replaced Jurgen Klopp at Liverpool this summer.
The former Feyenoord boss beat his old Ajax rival Ten Hag 3-0 on tour in the US last month, and the United manager believes Slot has inherited a better team from Klopp.
‘I’m not here to talk for him. But Liverpool, it's clear, they are in a different phase of the life cycle,’ said Ten Hag.
‘They have a team that is mature, players who have been playing for a long time together and who are very experienced. We have much more of a mix and have to build a new team.
Erik ten Hag (pictured) claims Arne Slot has taken on an easier challenge at Liverpool than he faced at Manchester United two years ago
‘I think the players, the partnerships, the relationships in that team are very clear and that is what he inherited. That has been built over the past years.’
Ten Hag has previously claimed that he inherited a ‘no good culture’ at United which has taken time to fix and is still in transition.
He added: ‘That was one of the reasons I wanted to come here – to have this challenge.
‘I knew beforehand that this was the most difficult thing I would ever do in my life, to come into a club where there were a lot of problems which we had to solve.
‘I inherited a history from six years of no trophies. That meant the dressing-room and the qualities were not right.
‘So we had to build, we had to construct, to perform and to bring up a higher level. What you see now is that we have brought in new players, many young players, and we are in a life cycle from the start.
‘We are still in the transition stage. Now we have to construct a team from it for the future.’