Many people get confused when it comes to the technical side of the paranormal. To be precise some people are confused about the terms 'ghosts' and 'spirits'. Some don't recognize or realise that there is a difference between 'ghosts' and 'spirits', even though in some ways they are the same in other ways there are very defining differences between them that makes them not the same thing.
I am going to try to simplify my explanation and try not to get too technical with you all. A 'spirit' is a person who has died and has 'crossed over into the light'. A lot of mediums use terms like 'crossed over' or 'crossed over into the light', and some people know what those terms mean but some don't. So for those who don't here's a quick and simple explanation, 'crossing into the light' means that when a person dies they pass quickly through the passage of light into the spirit world. Once they pass into the spirit world and through the light they become a 'spirit'. 'The Light' is merely the doorway or the passage/corridor that guides the deceased into the afterlife. A 'Spirit' can be a visitational spirit who goes back after there passing to the spirit realm to visit their family and friends left behind but they are based if you like in the spirit world on a constant basis.
Now, there's the term 'Ghost/Ghosts' which is a person who has died but for one reason or another has not chosen to 'cross over into the light' and go to the spirit world. The reasons can vary from a person have died so quickly they don't realise their dead so they don't 'cross over' like they should and sometimes need a bit of help to do so or can after a short time realise that they are dead and 'cross over' themselves. Sometimes a person dies and is confused and doesn't realise that 'the light' is for them to go into. Other times traumatic death's or regrets can leave a recently deceased person not willing to 'cross over' or not realising that they should. Those that don't 'cross over' are known as 'ghosts' and at times are also referred to as 'bounded' or 'grounded ghosts'. These terms are used in certain cases of 'ghosts' depending on the reasons for not 'crossing over' after they died.