The Canadian Army is organized into a headquarters (co-located in Ottawa with NDHQ), a Doctrine and Training System (HQ in Kingston), and four Land Force Areas (LFAs). From east to west these are: Atlantic, Secteur du Quebec, Central and Western. Each of these LFAs is commanded by a Regular Brigadier General, with one Reserve BGen as his second in command. Under the LFA HQ are (normally) one Regular Army mechanized Brigade Group and several Army Reserve Brigade Groups(a total of 10 across the Army), each commanded by a Colonel (Reg or Res respectively). LFAA has no Reg CMBG. Each LFA also owns an Area Support Group, which is equivalent to a formation and commands the support bases (Area Support Units) and the General Support Service Battalion (altough that is changing as we speak). Each LFA also owns at least one Area Training Centre where field exercises, range work and courses of instruction can be conducted.
Each LFA Commander is responsible for all Army activities in his area, from training to domestic operations to generating forces for overseas operations to looking after infrastructure: he has very big range of responsibilities, and commands both Regular and Reserve troops to achieve his assigned tasks. The Reserve CBGs contain a small number of Regular soldiers, but by regulation the senior CBG and unit command positions must be held by Reservists unless the Res is unable to produce a suitable candidate, in which case a Regular could fill the spot.
A Regular Mechanized Brigade Group usually consists of an HQ, a Signal Squadron that support the information systems and administrative needs of the HQ, a unit from the Armoured branch, an Artillery unit, one light Infantry battalion, two mech infantry battalions, and engineer unit, and a combat service support unit. Under the control (but not the "command") of the CMBG are a medical unit and a tactical helicopter unit.
The detailed organization of all of these units is changing as we speak under a program known as "Army Transformation", so it is becoming difficult to say exactly how a unit of any given type is organized other than in a generic way.
A Res CBG has no fixed organization and is primarily a trainining organization with a certain domestic operations capability (although this is changing too...). For example, the Res CBG I belong to consists of an HQ, two Armoured units, three Artillery units, five Infantry units and three combat service support units. Under our control but not our command are three Medical units. We are in the process of forming an Engineer sub-unit. Other CBGs are totally different: it is really a geographic and administrative grouping rather than an operational one.
Cheers.