Across the US the various states have established degrees of crimes.
Those degrees go to the severity of ana particular offense.
An attempted crime was meant originally to address a miscreant who failed to accomplish his misdeed, as in a person who was caught before he burglarized a home, or before he completed an armed robbery.
In many jurisdictions, people accused of a crime, say burglary, are often allowed to plead to the "attempt" to commit the crime.
In those jurisdictions, an attempt to commit a burglary is punishable by up to half of the maximimum for committing the crime.
In your example, OP, a simple way to look at any attempt is that is a lesser or included version of the crime itself.
Murder (the degree aside) versus attempted murder.
By the way, the victim can be dead, and the perpetrator can end up pleading or being convicted of attempted murder, versus murder (degree aside).