The difference between the standard and sequence of Oracle database

The two are totally different things.
Cursors are based on the query result set
Let's say that one of your SELECT statements queries a result set of several records, and if you want to make a judgment or other action on each row in the result set, then the SQL statement update or the specific action for each row will not be satisfied, and this time the cursor will work:
You can define this result set as a cursor, and you can iterate through each row of records in the result set and manipulate it by using the cursor, which means you can iterate through the operation data by executing a for loop on the results of a select query.
And the sequence is an object in Oracle, just like a table, a view, you can build a table: Create TABLE ...
To build the sequence: Create sequence ...
It's just that its structure and function are different from the table, which is a sequence of automatically added numbers for a rule, typically used as a surrogate primary key, or as an ordinal generator.

Differences between the target and sequence of Oracle databases