I think you are asking how Freshmen & Sophomore college students interact with Junior & Senior college students in the USA. If that is your question, then I can share my experiences and observations.
What I have seen among college students in the United States is that Freshmen tend to hang out (interact) with other Freshmen. The same can be said for all levels of college students. For the most part, college students in the USA tend to interact with other students who are in their same year group.
There are some student organizations and sports that provide an opportunity for lower level students and upper level students to interact, but these interactions are the exception, rather than the rule. At least that is my observation and experience.