OK, first let's get it straight;
The phrase used by US, Canadian and Central American controllers is:
"Taxi into Position and Hold" [U]not[U] "Position and hold"
The "hold short" command is given by the tower when an aircraft is either waiting to cross an active runway or is waiting to take-off. In either case when a "hold short" command is issued it is required to be read back by the pilot. A failure to read this clearance back will result in the tower repeating the instruction and requesting a read back.
To achieve any possible confusion between the two a pilot would have to hear a partially blocked transmission with all the words blocked except the word "hold", which, if that happens, the pilot should then ask for clarification.
If we really want to address an issue of safety here it should perhaps be directed at the issuing of Position and hold or line up and wait clearances at night or in low vis conditions. At least during a clear day if someone taxis onto an active runway the landing aircraft will be able to see it and initiate a go-around.
Changing phraseolegy may only open up another can of worms as a new previously unthought of confusion may result.