There is also a further sub division of felony based on a class code which determines sentencing.
Regardless, it is very rare for someone doing that little time to do so in a state of federal prison, and most studies on this data are based on the department of prisons data, which is why it's not typically included.
Many felons get probation after serving time, this is the only term I've heard felony probation applied to, what are you referencing to mean?
In the United States, where the felony/misdemeanor distinction is still widely applied, the federal government defines a felony as a crime punishable by death or imprisonment in excess of one year. If punishable by exactly one year or less, it is classified as a misdemeanor. The classification is based upon a crime's potential sentence, so a crime remains classified as a felony even if a defendant receives a sentence of less than a year of incarceration.
Also, no, I wasn’t referring to post-release supervision (which is usually referred to as parole or supervised release). Many hundreds of thousands of people every year receive a sentence of probation for felonies, primarily because countless “tough on crime” measures have increased maximum sentences for minor crimes, which automatically turned them into felonies where they used to be misdemeanors.