A subtle difference is so slight that it is difficult to detect or describe.
EXAMPLE: The two shades of green were so subtle, that you needed to put them next to each other to tell that they were not the same color.
To avoid being obtrusive in the elegant restaurant, he used subtle gestures to call the waiter to his table.
A simple sentence uses a subject and a verb..
Some spices have a subtle aroma. The wink she gave was no subtle clue.
She chose fabrics in subtle shades of grey.
The subtle nuances of the English language make many of these questions difficult to answer.
Not many people noticed the subtle humour in his remarks.
The dawn revealed subtle nuances in the coloration of the rocks. That hint was not very subtle.
Complex (APEX)
I gave my friend a subtle hint from across the room.
Like this; I am an architect.
I am unsympathetic to your need.
i think politicaly