OP: Interesting that you opted to be sparse about your thoughts. Result might be more of a general discussion than one tailored to your concerns.
Both are great schools where you are likely to meet very nice people. Maybe an odd comment, but true in my experience–and I know a significant number of graduates from both schools. But they will be different in other respects.
As a pre-med, ND becomes at least as attractive as Ivy League Dartmouth College as a primary advantage of Dartmouth is that it places well in the financial & consulting industries among others.
Because I do not know your specific concerns, I will offer ratings found in the Fiske Guide To Colleges 2020:
Notre Dame has 4 out of a possible 5 Pens for Academics, 3 Telephones for Social Life, and 3 Stars for Quality of Life.
Dartmouth College: 5 Pens for Academics, 5 Telephones for Social Life (indicates that Fiske considers Dartmouth College to be somewhat of a party school even though outstanding academically as signified by the 5 Pens rating for Academics), and 3 Stars for Quality of Life.
Overlap Schools:
Dartmouth College overlaps = Brown, Duke, Yale, Stanford, Princeton, Colgate, Middlebury, & Williams College.
Notre Dame overlaps = Vanderbilt, Boston College, Northwestern, Harvard, Duke, Holy Cross, & Villanova.
Duke is the common overlap school for Notre Dame & Dartmouth College. And Duke seems to be a reasonable mixture of both schools in my opinion. Nevertheless, I do not see Dartmouth College students & Notre Dame students as interchangeable.