Going by wikipedia jolly_roger more or less refers to any pirate flag. The skull_and_crossbones is just apparently the traditional flag, but it isn't restricted to it. It does say "the flag most commonly identified as the Jolly Roger today is the skull and crossbones, a flag consisting of a human skull above two long bones set in an x-mark arrangement on a black field." Also merriam-webster also defines the Jolly Roger as "a black flag with a white skull and crossbones formerly used by pirates as their ensign." Although if you do a google search for "jolly roger" you'll come across plenty of images that are a skull and crossed swords.
There is also a pirate_flag tag as well.