2nd amendment
A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed
14th amendment
section 1, clause 2
No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States
The right of the people to keep and bear arms is in the Constitution.
The 14th Amendment said the state can't make laws that abridges the privileges or immunities of the citizens. The right to bear arms is a privilege established in the 2nd Amendment; so the states can't infringe on this.
Abortion does not appear in the Constitution, so it is up to the states or Congress to determine its status.