SAME and ALL_DIFFERENT

SAME(a, b [, ...]) checks whether the supplied elements share one identity. ALL_DIFFERENT(a, b [, ...]) checks that their identities are pairwise different.

MATCH (a:Person {name: 'Alice'})-[:Knows]->(b)
LET alias = a
RETURN SAME(a, alias) AS same, ALL_DIFFERENT(a, b) AS distinct_people;

Both results are true. Identity includes graph, node/edge kind and row ID; matching properties or labels is not enough. Aliases preserve identity. Null element operands participate in nullable predicate semantics, so do not use these as replacements for IS NULL tests.