The M69 uniform resembles the classic western-style suit and tie getup. A green tie and khaki shirt accompany a khaki-colored service uniform, and a black tie and white shirt accopany the parade uniform. I get that much.
But I don't see pics of the shirts alone anywhere, at least if these shirts are like the regular button-down shirts I wear to work each day. I have seen pictures of white and khaki shirts that have shoulderstraps on them, though, which I always assumed were a different uniform alltogether. Now I suspect that I was wrong.
So the question is were the shirts with shoulderstraps worn underneath the jacket of the M69 uniform, like in the pics below?
This was only true for M1969 shirts. M1955 and sometimes M1958 uniforms wore different shirts.
Also, general officers shirts differed from other officers shirts in that they had elasticated sides and press studs on the pockets and were also of better quality.
Yes, enlisted shits (as far as I can remember, don't have the waiste buttons at the sides and don't have breast pockets. Its so long since I've seen one (all mine are in storage at the moment).
Also,
They are of a slightly browner colour.
If you are talking about the conscripts then yes, they have the loops on the shoulders, in fact, I think all of them have loops on them with two holes to attach a button when it is worn as a hot weather service uniform.