If you are new to scouting, the following terms may help you understand the structure of the cub scouting program:
PACK—A Pack is a group of Cub Scouts, adult leaders, and parents who belong to the same cub scout unit (e.g., Pack 130 of the Apollo District, Sam Houston Area Council).  Each Pack is made up of Lion, Tiger, Wolf, Bear, and Webelos I and Webelos II (aka Arrow of Light) dens. The Pack consists of a group of Dens that meet together about once a month.  The Pack is composed of Dens and Parents of the scouts who are members of those Dens.
DEN—A group of scouts, organized by grade level, and supervised by Den Leaders.  Each den meets at certain times to work on achievements and other activities. The den is led by adult Den Leaders and Assistant Den Leaders (parent volunteers) who plan and conduct den meetings. 
CUB MASTER—The adult program leader of the Pack.
DEN LEADER—An adult who accepts the responsibility of guiding a Den.
PACK COMMITTEE MEMBER—A parent who serves on the Pack Committee.
DEN CHIEF—A scout appointed by his or her Scoutmaster to help the Den Leader with the Den operations. Cub Master should contact Scoutmaster for a Den Chief.
BOBCAT—The entrance requirements for Cub Scouting, passed by all scouts regardless of age.
LION—The rank earned by Kindergarten Cub Scouts.
TIGER—The rank earned by 1st grade Cub Scouts.
WOLF— The rank earned by 2nd grade Cub Scouts.
BEAR—The rank earned by 3rd grade Cub Scouts.
WEBELOS—The rank earned by 4th grade Cub Scouts.
WEBELOS ACTIVITY BADGE—An award for completion of the requirements in one of the 20 Webelos Activity areas.
ACHIEVEMENTS—The required activities for earning the Wolf and Bear badges.
ELECTIVES—the optional activities used by Wolf and Bear Cub Scouts to earn Arrow Points.
ARROW OF LIGHT—The Arrow of Light is the highest Cub Scout award.  It may be earned by 5th grade Webelos.