Here is one picture of the plant I am referencing in 7/24 post. The right hand side of the plant makes up 80% of the plant. The left hand side of the plant makes up the remaining 20%. The left hand side is one entire branch that is growing out of the main stem of the arborvitae (or dwarf pine?). It is NOT a separate stem with roots. Here the difference needles are visible.

still trying to upload pic

Here it is from a distance.

I am pretty sure what you have in NOT an arborvitae. It looks like the plant on the right is a dwarf Alberta Spruce. The plant on the left also looks like a type of spruce. Sometimes plants do produce what are called "sports". This just happens spontaneously. But it is very cool. Arborvitae don't produce needles. Their leaves are flattened and somewhat scale like. Hope this helps.