Trying to sync new music i got on my mac which is my new computer to my iPhone and erase and sync is saying it will replace the contents of my phone. Does it mean Photos also or just Music and Videos?

I got a Mac and i downloaded new music on it and im trying to sync the music on this computer to my iPhone which is hooked up to another iTunes and iTunes is saying " An iPhone can be synced with only one iTunes Library at a time. Erasing and syncing replaces the contents of this iPhone with the contents of this iPhone with the contents of this iTunes library" does this mean that it will also erase my photos or just my music and videos ?? if it does is there another way to sync with out all my contents being deleted??