Technically, they’re the same thing;  however, people tend to use the terms differently.

“Femicide” is used for:

  • murder of a woman by her intimate partner or family member
  • murder of a woman because she is the the partner / relative of a male enemy
  • for example, murder of the girlfriend / sister of a rival gang member

We lose 60,000 women per year to femicide. — UNWomen

“Gendercide” is used for:

  • death of females due to lack of rights and discrimination so severe that many women & girls simply do not survive

We lose 3.5 million women per year to gendercide.  — UN Population Fund, UNFPA

In common usage, femicide is a type of gendercide.  Although femicide accounts for fewer deaths than gendercide, these killings, frequently characterized by “overkill,” hold special significance for  their sheer brutality and their strategic use to intimidate and subordinate women.