Detachments Vs Formations

[Coverfire]

 I was thinking that Formations were synonyms for detachments but unless I am mistaken I can use formations to create the detachment?

 

so an example would be...

 Company of the Great Wolf Detachment.

 Minimum - 1 HQ, 2 Elite

 

 Could be comprised of 

 Wolf Guard Battle-Leader and a Thunderstrike Formation (i.e. 2 Wolf Guard units)

[Valerian]

Nope.  Read this thread.   In your example, the Thunderstrike Formation is a distinct, modular, 'special' Detachment within your Battleforged army.  You cannot "double-count" the units that are in the Formation as also being in your Company of the Great Wolf Detachment.

 

V

[Kilofix]

Also note that Formations don't always have the Special Rules that the Detachment from the same Codex / Supplement provides.

 

Like the Champions of Fenris Formation - Grimnar's War Council does not have the Kingsguard nor Grimnar's Right Hand Special Rules which the Champions of Fenris Detachment provides.

 

And, remember that the Champions of Fenris Detachment doesn't have the Objective Secured Special Rule that the BRB - Combined Arms Detachment provides.