Infantry Formations
During combat three main formations were used by platoons, companies and battalions: (Skirmish) Line, Wedge and Broad Wedge. Of these, Squads only used (Skirmish) Line, but they also added (Skirmish) Column.
(Skirmish)
Line
All sub-units next to each other. Squads would form a ragged line, rather than straight line.
This was the most common formation for Squads once in combat.
For Squads and Platoons the Russians used the term "Skirmish Line" rather than "Line". See Unit Frontages for expected distance between men.
When attacking at night the Russians preferred organizing the platoons of each company in Line (Sharp, 1998).
Wedge
"One up, two back". One sub-unit in front and two echeloned behind its flanks, but not directly behind the point sub-unit.
When attacking in woods the Russians preferred organizing the platoons of each company into Wedge (Sharp, 1998).
Broad,
Blunt or Reverse Wedge or Rhomboid or V
"Two up, one back". Two sub-units in line next to each other and the remaining one (or two) behind.
Different nationalities used different names for this formation. The Germans used the term "Blunt Wedge" (U.S. War Department, 1995). The Russians used the term "Broad Wedge" for platoons, companies and battalions, but the term "Reverse Wedge" when the same formation was adopted by anti-tank rifle squads (Sharp, 1998). I'm not sure what the official British term was, but colloquially it is called a "V".
Broad Wedge seems to have been the preferred Company formation in both attack and defense. It also seemed to be the preferred Platoon formation in prepared defenses.
Generally the unit HQ didn't have a fixed location in this formation. The British at least had the Company HQ adjacent to the rear platoon (Lucas, 1982). The Russians also used a variation called the " Rhomboid" for a platoon attacking in woods; apparently this differed from a normal Broad Wedge by having the platoon HQ between the lead Squads (Sharp, 1998).
Russian
Battalion Broad Wedge
A Russian battalion in Broad Wedge is described a little differently: "2 companies in line next to each other and one company echeloned behind the left or right flank" (Sharp, 1998, p. 7). The implication is that this is the left or right outer flank of the forward line (as per diagram). If, however, the flank in question is an inner flank, then suddenly it becomes the normal Broad Wedge.
British
Battalion Broad Wedge
British Infantry Battalions had their four companies with two companies up front and two behind (Lucas, 1982). Other nationalities considered this a Broad Wedge, but to to be honest I don't actually know the term the British used for this formation.
(Skirmish)
Column
A squad Column was single file of men. Sharp (1998) also mentions a "Skirmish Column" but doesn't explain how it differs from a column. I presume a Skirmish Column had the men spread out like a Skirmish Line - see See Unit Frontages for expected distance between men. These long Skirmish Columns were used for reconnaissance missions, i.e. when marching but expecting enemy.
A platoon Column was a file of squads each of which is in Column or Skirmish Column.
Variations on column were used for marching outside combat range. Presumably, a normal Column, as opposed to the Skirmish Column, had the men closely spaced. A Double Column was a column of men with two files. The Germans also had a variation called March Order. This was a column with three files, which for a squad also meant 3 ranks.
References
Erickson, J. (1993). The Road to Stalingrad: Stalin's war with Germany: Volume One. London: Weidenfeld.
Gajkowski, M. (1995). German Squad Tactics in WWII. Pisgah, Ohio: Nafziger Collection Inc.
Hastings, M. (1984). Overlord: D-Day and the battle for Normandy 1944. Papermac.
Lucas, J. (1982). War in the Desert: the Eigth Army at El Alamein. Arms and Armour Press: London.
Medley, R. H. (1990). Five Days to Live, France 1939-40. Dover & Company.
Sharp, C. S. (1998). Soviet Infantry Tactics in WWII: Red Army Infantry Tactics from Squad to Rifle Company from the Combat Regulations. George Nafziger.
U.S. War Department. (1995). Handbook on German Military Forces. Author.
I haven't actually seen this book, so I am relying on comments made by Bill Own on the Spearhead Discussion Forum.