Go into all the world vs lost sheet of Israel

Old Covenant

Matthew 15:24
New King James Version (NKJV)

²⁴ But He answered and said, “I was not sent except to the lost sheep of the house of Israel.”

New Covenant 

Mark 16:15
New King James Version (NKJV)

¹⁵ And He said to them, “Go into all the world and preach the gospel to every creature.