The cells that that contain  in the diagram below would work as both:
It can be either solution.
We presume that a Sudoku problem can’t have two solutions.
, on the other hand, can’t be switched around. They wouldn’t be switched within the same box, so the numbers can’t be switched.
Like the diagram, this is a pattern where the  can be switched around. If it can be switched, it wouldn’t work as a Sudoku problem, so in the cells indicated in red, either a  or  is entered.
In this pattern, one of the upper two cells with , will definitely be a . Hence,  won’t go in the cell marked red and it will be a .
In this pattern, one of the lower two cells with , will definitely be a . That means,  can’t be in the other cells in the box. Also, a  can’t be entered in line H of the boxes to the left and right.
An  or  will definitely be entered in either the  cell or  cell. There is a cell at the very bottom with  as candidates. If an  is entered in the blue cell above, then the pink cell will be a . If the blue cell is a , then the pink cell will be an , so  or  can’t be entered in the cells marked with X’s.
An  or  will definitely be entered in the  cell or  cell. The pink cell only has  as candidates. This means if an  or  is entered into either one of the blue cells, the pink cells will become  or , so  can’t be entered into the cells marked with X’s.
An  or  will go into either one of the  cells below. However, there are no open cells in this line where a  can be entered. Therefore, a  will have to go in one of the blue cells below, so a  can’t be entered into one of the blue cells at the bottom.
Lets examine the  cells. In this line, a  can’t be entered into any of the empty cells. This means, in either one of the  cells a  has to be entered, and  can be eliminated as a candidate.