It is not.
There are two ways to deal with this.
First is to separate them into expressions.
11t - 3t is made up of 11t and -3t
3t - 11t is made up of 3t and -11t
As you can see the negative sign are different from each expressions, therefore they are different.
Another way to see it is to solve them.
11t - 3t = 8t
3t - 11t = -8t
The answers are not = so they are not equivalent to each other.