Equal set =>Two sets are equal if they both have the same members.
Example
If, F = {20, 60, 80}
And, G = {80, 60, 20}
Then, F=G, that is both sets are equal.
Note: The order in which the members of a set are written does not matter.
Equivalent Set=>Two sets are equivalent if they have the same number of elements.
Example
If, F = {2, 4, 6, 8, 10}
And, G = {10, 12, 18, 20, 22}
Then, n(F)= n(G)= 5, that is, sets F and G are equivalent.
Now Let's take Your Example
A={1,2,3}
B={1,1,3,3,2}
According to definition these two sets are equal because both sets have exact same elements.Don't think 1,1 and 3,3 as "two element of the same value" .They are the same element really and an element is either a member of a set or it is not.
So these two sets are equal sets but not equivalent sets and It is not necessary for equal sets to have same number of element.
