Oracle is a software company that produces a number of software products, mainly database products for large corporations. See
Oracle Corporation - Wikipedia, the free encyclopedia.
A spreadsheet is a table of information laid out in rows and columns. Very frequently used for financial calculations but certainly for a multitude of other uses. See
Spreadsheet - Wikipedia, the free encyclopedia.
So a better comparison is a database to a spreadsheet. A database is a collection of data stored in a computer system. See
Database - Wikipedia, the free encyclopedia.
Generally, I use a database when I want to keep track of a collection of things and then search on that collection (or list) or produces reports about that list based on certain characteristics. For example, I might do a search to find a person's name in a contact database or how many people in my contact database live in Michigan.
While a spreadsheet is essentially a collection of data as well and can be used as a database, it is better suited for performing calculations, such as a budget or sales information for example. A spreadsheet program like Microsoft Excel has many calculations build into it such as average, sum, min, max, etc. that makes working with numbers very convenient.
This is obviously a very high-level overview, but hope it helps.