NASHVILLE, Tenn. » The cases are tragically similar: Student-athletes at two elite universities accused of sex crimes against unconscious women. Yet one is given six months in a county jail, while the other is facing at least 15 years in prison.

Some have questioned why 20-year-old former Stanford swimmer Brock Turner, who is white, received a far less severe sentence for a January 2015 assault than the one faced by former Vanderbilt football player Cory Batey, 22, who is black. The differences have taken on added significance this week as a white former teammate of Batey’s, Brandon Vandenburg, stands trial again in Nashville for his role in the dorm room assault, which took place in June 2013.

But the comparison is not so simple.

The difference in punishment reflects the number of alleged perpetrators in one case, the acts committed, overwhelming evidence documenting one of the crimes, and variations in how rape is defined in Tennessee and California.

“It does seem like an extreme disparity, but I would say this: With these sex crimes, the facts are very important, the details are very important, and the law punishes the conduct differently depending on what conduct can be proven,” said Dmitry Gorin, a Los Angeles criminal defense lawyer and former prosecutor specializing in sex crimes. “In the Stanford case, they did not prove rape.”

The two cases have moved to the forefront of a national debate about sexual assaults on the nation’s college campuses and the conduct of student athletes. And some critics insist the circumstances are too similar to justify the discrepancy.

Misee Harris, a Los Angeles-based blogger who used to live in Tennessee and writes extensively about race issues, has been among those criticizing how the two cases were handled. She says neither punishment hit the mark.

“One is just excessive and the other is just a little too lenient,” Harris said.

The Stanford swimmer was convicted of sexual assault, not rape, after two students discovered him on top of an unconscious woman behind a dumpster. The four former Vanderbilt students, three of whom are black, were charged with aggravated rape. If Vandenburg is convicted, he faces the same sentence as Batey: a minimum of 15 years in prison with no parole.

The aggravated rape charges came into play under Tennessee law because the victim was unconscious and there was more than one alleged perpetrator. Two of the Vanderbilt players were charged with aggravated rape even though they did not have sexual contact with the woman because prosecutors considered them active participants.

In the cases of both Batey and Turner, the suspects and victims say they were drunk and remember little or nothing. Legal experts say that puts added weight on physical evidence, which was far more substantial in the Vanderbilt assault.

The Vanderbilt case included graphic evidence, such as cellphone videos and photos. No photo or video evidence surfaced in the case against Turner.

Another key distinction involves how the two states view the crime. Juries in both cases concluded that digital penetration took place but found that sexual intercourse had not been proven. Tennessee law considers digital penetration to be rape; California does not.

Turner, in fact, was not even charged with rape when he went to trial in March.

“They chose not to prove rape because they did not have the evidence for it, according to the records and the press reports,” said Gorin, the Los Angeles attorney. “In the Tennessee case, they proved aggravated rape, and the law in the different states punishes the conduct differently.”

California has minimum 15-year sentences for certain types of aggravated rape, Gorin said, but that’s not what prosecutors proved in the Stanford case. The lesser charges Turner was convicted of in March carried a maximum of 14 years in prison, and prosecutors asked that he spend six years behind bars.

However, the judge did not have to adhere to a strict minimum and gave him six months instead. Tennessee law does not grant the same discretion to judges in aggravated rape cases, said Rob McKinney, a Nashville lawyer and expert in Tennessee criminal law who is familiar with the case. That means the judge in Batey’s case must sentence him to at least 15 years in prison when he is sentenced in July. The same is true for Vandenburg if he is convicted, and the charges against both carry a maximum of 25 years in prison.

“That is the floor, not the ceiling,” said McKinney, addressing Batey’s sentence. “He’s not getting out of it. He’s going to go to prison.”