Bob is charged with a felony and Sally is charged with a misdemeanor. Who likely will receive the harsher sentence and why?

Normally the felony would get a harsher sentence but there are a lot of other factors that can be taken into consideration. Since you are not being specific, I can't address your case but some of those factors could be that Sally has a long record and Bob does not or someone was hurt by Sally but no personal injury was involved with Bob's case.