ELI5: Voiced and Voiceless differences (in description)

I'm having a really hard time distinguishing exactly what makes a voiced and voiceless sound. Take the /ð/ and /θ/ as examples, both the dental fricatives (th).

Websites tell you to hold your throat, make these different sounds, and feel a difference in the vibration, but I'm really not getting any difference. Can someone explain it deeper, or tell me some other alternative? Thanks!