Icloud holds
http://support.apple.com/kb/PH12519Purchase history for music, movies, TV shows, apps, and books
Your iCloud backup includes information about the content you have purchased, but not the purchased content itself. When you restore from an iCloud backup, your purchased content is automatically downloaded from the iTunes Store, App Store, or iBooks Store. Some types of content aren’t downloaded automatically in all countries, and previous purchases may be unavailable if they have been refunded or are no longer available in the store. For more information, see the Apple Support article iTunes in the Cloud availability by country. Some types of content aren’t available in all countries. For more information, see the Apple Support article Which types of items can I buy in my country?.
Photos and videos in your Camera Roll
Device settings
App data
Home screen and app organization
iMessage, text (SMS), and MMS messages
Ringtones
Visual Voicemail
Your music is in your iTunes.
When you boot up the iPhone 6 opt to use your iCloud back up and not as a new device.