Hi Dawn,
Joye is short for
joyetech. They are the *original* manufacturer of the 510 atomizer and all the original 510 based e-cigs. Other companies however make 510 style/compatible atomizers. Some of those companies make good products, some not so good.
Most vendors will either state on their site, whether the atomizers are genuine Joyetech. If they do not, you could try e-mailing. Some companies sell more than one 510 manufacturer. Some companies are Joyetech only.
Nope that helps.
Since I'm a mod, I do not like to name vendors often. However Janty, Cignot, and Freedom Smoke USA all carry genuine Joyetech equipment. And many others (see the vendor forums) do also.