SA Armour shoulder titles

[Milmed]

I'm trying to find out why the SA Armour units have different colour shoulder titles. Some are white unit names embroidered on blue felt and others are blue unit names embroidered on orange felt.

Is this related to specific periods and if so which came first and when was the changeover. Or is it possibly related to Permanent Force units vs. Citizen Force units?

Here are the variations I have seen:

White on Blue Shoulder Title Arcs.
OPL REGT 1 SDB
1 SSB TRG REGT
1 S D B
1 S S B
2 S D B
2 S S B
SCHOOL of ARMOUR
PANTSERSKOOL

Blue on Orange Shoulder Title Arcs.
1 S D B
1 S S B
2 ARMD C REGT
2 PANT K REGT
2 S D B
2 S S B


Steven