Hi,
I guess I could go on and on...but I'll keep it short.
Doug is right. All the different names/spellings are the same art. Descended from Yoshin ryu, Yoshin Koryu and Tenjin Shinyo ryu. Shindo Yoshin ryu (as we spell it) is the same art Otsuka Hironori combined with Okinawan Karate to create Wado ryu. It is commonly believed that Otsuka Hironori was "the" headmaster of SYR. This is not true. Three different lineages exist. The mainline was headed by Matsuoka Tatsuo, not Ohtsuka. Otsuka inherited the Nakayama line which today survives as Wado ryu Jujutsu Kempo, a companion art to Wado ryu Karate
I hope that helps,
Toby Threadgill, Soryushin Dojo
Takamura ha Shindo Yoshin ryu