 Usage:

ZDIFFSTORE destination numkeys key [ key ... ]
 Complexity:
 O(L + (NK)log(N)) worst case where L is the total number of elements in all the sets, N is the size of the first set, and K is the size of the result set.
 Since:
 6.2.0
Computes the difference between the first and all successive input sorted sets
and stores the result in destination
. The total number of input keys is
specified by numkeys
.
Keys that do not exist are considered to be empty sets.
If destination
already exists, it is overwritten.
Examples
127.0.0.1:6379> ZADD zset1 1 "one"
(integer) 1
127.0.0.1:6379> ZADD zset1 2 "two"
(integer) 1
127.0.0.1:6379> ZADD zset1 3 "three"
(integer) 1
127.0.0.1:6379> ZADD zset2 1 "one"
(integer) 1
127.0.0.1:6379> ZADD zset2 2 "two"
(integer) 1
127.0.0.1:6379> ZDIFFSTORE out 2 zset1 zset2
(integer) 1
127.0.0.1:6379> ZRANGE out 0 1 WITHSCORES
1) "three"
2) "3"