K9 is a TV series and hence been put out there for a general audience to see unlike the other things
K9 is a TV series unlike Reeltime Pictures
I was not able to put this into the edit summary before but per Epsilon's comments about a lot of things like Reeltime Pictures, the difference between K9 and all those other things is that K9 is a TV series and hence been place out there for a general audience to see unlike the other things which we as Doctor Who fans know about and know where to find them if we wanted to.