Mark 16:16: Belief, Baptism, and Salvation
Mark 16:16 pairs belief with baptism in its promise but names only disbelief in its warning. The verse makes faith the dividing line while treating baptism as the believer's ordinary response.
Mark 16:15: Sent to Preach to All Creation
Mark 16:15 places the command to preach in the mouth of the risen Jesus, spoken to disciples who had just failed to believe. The scope is the whole creation; the task is announcement.