If all you are doing is storing and serving data, both the Xeon and i3 are unnecessary. A Pentium would more than suffice.
Really, you only need to get into an i3 if you have a use case for the additional CPU power (like video transcoding), or you might get a Xeon if you are encrypting your pool and would benefit from the AES capabilities of the Xeon.
Frankly, a Xeon is overkill is almost all home-use cases (especially if you are budget conscious), and if it's not overkill for your use case, you'd know it.