Iphone custom ringtone and text tone names questions..

I assume that text tones and ringtones both should end in .m4r I have quite a few of these on my Android and these are stored in separate locations but are MP3.

I think from what I gather is that the iPhone stores the .m4r files regardless if ringtone or text message tone in the same place.

Therefore I should use appropriate file names for each to aid me when I select a ringtone or a text tone for a contact or other purpose

Is this a correct assumption?

Thank you very much in advance, Peter