Files of song ringtone and movie ringtone are actually the same.
                The one that extracts audio section from the movie ringtone is the song ringtone file. 
                
                  
                    | Format Name | 
                    Carrier, Series | 
                    Video | 
                    Audio | 
                   
                  
                    | 3GPP | 
                    DoCoMo FOMA 
                    vodafone | 
                    MPEG-4 | 
                    AMR 
                    AAC  | 
                   
                  
                    | 3GPP2 | 
                    au WIN | 
                    MPEG-4 | 
                    AMR 
                    AAC 
                    qcp  | 
                   
                  
                    | AMC | 
                    au EZmovie
                     | 
                    MPEG-4 | 
                    MP3 
                    qcp | 
                   
                   
                
                There are formats that has only song ringtone, without image.
                There seems no models of mobile phones are able to play MP3 files directly.
                I think this is because MP3 files do not have the copyguard system that prohibits transfers. 
                
                  
                    | Format Name | 
                    Carrier, Series | 
                    Video | 
                    Audio | 
                   
                  
                    | AMR | 
                    vodafone | 
                    - | 
                    AMR | 
                   
                  
                    | AAC  | 
                    Song Ringtone | 
                    - | 
                    AAC  | 
                   
                  
                    | HE-AAC(AAC Plus)
                     | 
                    au Song Ringtone(Full Version) | 
                    - | 
                    HE-AAC | 
                   
                 
                 |