A conviction is a conviction--regardless whether a jury finds a defendant guilty, whether a judge finds him guilty after waiver of a jury trial, or whether the defendant convicts himself with his own words in a guilty plea. There is no such thing as a "no contest" plea or an "admission to sufficient facts" in Federal court.
The Federal sentencing guidelines were supposedly designed to bring uniformity and eliminate much of a judge's sentencing discretion which often resulted in a great disparity in sentences imposed for the same crime by different judges, and in a way, to eliminate the so-called "trial penalty" some judges would slam onto a sentence for "wasting their time" by insisting on a trial. There is a range of minimium and maximum terms set forth, which a judge is pretty much going to choose from. He has to justify a so-called "downward departure"--ie a sentence less than the minimum called for in the guidelines--in writing, and unless it is an agreed upon departure, the Government can appeal it. Federal courts don't have suspended sentences, either. You serve 85% of the sentence actually imposed. If there is such a thing as community service in Federal sentencing, it's reserved for the most trivial federal misdemeanors, or imposed as something to be performed after service of the prison sentence.
Don't think that the run of the mill Massachusetts District Court dispositions that you read in the court report section of your local paper reflect what happens in a Federal District Court
It's a different ballgame, with professional, and often career, prosecutors, smarter and more qualified (and often tougher) judges, with rules of evidence designed to facilitate convicting people, and where the Government rarely loses.