Goshinjutsu is one of the names that William Chow used to describe his Kenpo style.
Sure, that's one example… as said, it's a fairly generic term.
When I have seen it used, the school usually has a connection to Okazaki/Chow/Chow-Hoon/Wally Jay/Kufferath.
Cool.
I am not familiar with Goshin jujitsu.
Yeah… sorry, I kinda missed that part in my answer…
There are a number of modern systems that have named themselves "Goshin Jujitsu" (note the spelling), "Goshin Ryu Jujitsu" (again, spelling), or similar… they are almost all eclectic mixes of judo, aikido, and karate, often with some basic BJJ or similar, sometimes claiming to be "traditional Japanese Jujutsu" (uh… nope). In regards to what they're like… that really depends on which particular group using the name you're asking about.
My instructor says it's the self defense portion of judo that's not allowed in competition. Since our class is mostly police and military....actually it's all police or military.... He teaches a lot of standing arm control, defense from people grabbing you some weapons disarms and a lot of the leg locks and other grappling that was taken out of sport.
Sort of, yeah…
Within Judo, the term Goshinjutsu is specifically used to refer to the last set of kata added to the syllabus in 1956, the Goshin Jutsu no Kata. These were, in essence, an updated set of defensive techniques to take over from the Kime no Kata (Forms of Decisiveness/Decisive Action), mainly to deal with more modern attacks/weapons, such as pistol.
The kata look like this:
Along with a number of other kata (such as the aforementioned Kime no Kata), this set contains methods that are not legal in competition, as your instructor stated.
Of course, that's simply the Judo application of the term… outside of Judo it refers to basically self protection skills.