A second home is for your "exclusive use and enjoyment" and cannot be occupied (by you) for more than a few months of the year to be considered a 2nd home. That said, because occupancy fraud is rampant, if you have 2-3 rental properties out of the area and want to add a new "2nd home", most lenders will significantly question your motives and perhaps require the purchase to be considered a rental rather than a true 2nd home.
If conforming loans are 7 for an owner occupied purchase, a 2nd home will be about 7.25, and a non-owner loan rate will be in the upper 7's. Most jumbo lenders are very shy about investment purchases so these better rate products may be difficult to obtain.