There are several reasons why someone might say that every session of Congress will be different:
Different legislation: Every session of Congress sees the introduction of new legislation and the consideration of existing legislation. This means that the issues and priorities being discussed and debated will change from session to session.
Changing political landscape: The makeup of Congress changes from session to session, as new representatives and senators are elected and incumbents are re-elected or replaced. This can lead to different political dynamics and power dynamics within Congress.
Changing public opinion: Public opinion on various issues can change over time, which can influence the priorities and actions of Congress.
Changing global context: The global context in which Congress operates can also change from session to session, affecting the issues and priorities that are relevant to Congress.
Overall, these factors contribute to the dynamic and constantly changing nature of Congress, making it likely that every session will be different in some way.