Which act of murder is different from the others?
Femicide, also called gynocide, is a killing in general, while the others focus on family members. Another difference is femicide is the killing of women, while the others are all male.
Femicide: the systematic killing of women
Patricide: the killing of one's father
Fratricide: the killing of one's brother
Nepoticide: the killing of one's nephew.
There are more names for male killings (patricide - father, fratricide - brother, nepoticide - nephew, avunculicide - uncle, mariticide - husband) then there are names for female killings (matricide- mother, sororicide - sister, uxoricide - wife). Almost all other homocides, family or in general, are not gender-specific.
More Info:
en.m.wikipedia.org