(as of July 2015)
Working groups are established by an NRSC subcommittee for specific purposes, such as (but not limited to) developing a draft of a specific standard or specification, and are to be dissolved by the Chair of the parent body when their function is no longer required.
Task groups are ad hoc bodies that are formed by an engineering committee, subcommittee, or working group to address a specific problem as part of the larger body. Task groups meet informally and do not have a standard-formulating mission. They are dissolved by the Chair of the parent body when the purpose for which they were formed has been completed.