Ok, I suppose you'd like me to explain those for you. They may or may not be what you were expecting, but in my world an orb, mist, funnel, apparition, white noise, ouija playing, etc. etc. etc. ghost is still just one thing - a human spirit. And now for the explanations:
1. Guardian Angels - Everyone has at least one. They are usually some kind of relation to you that died before you were born. Most of the time you won't know who they are - or rather, were. They watch over us our entire lives and help us out through the rough and dangerous times. They're the little voice telling you not to take your usual route the day a huge pile-up happens on the freeway. That's just an example but I think you get what I mean.
2. Lost Souls - These are spirits who know they're dead but don't know where to go. They can also fear moving on and are afraid to leave what's known to them. They linger around until the day comes when they're ready to leave.
3. Are We Dead Yet? - An easy example of this is Bruce Willis' character in The Sixth Sense. These spirits walk around, going about their lives not knowing that they've passed on. They wonder why people ignore them and why nobody comes to visit anymore. This happens more often with old people who've spent their later years by themselves. Another (fictional) example is the Nicole Kidman movie, The Others. The spirits may think that the new inhabitants are the spirits, when it is the other way around.
4. Unfinished business - There can be a number of reasons why certain beings stick around after death. As portrayed most often in movies - "catch my killer!" Other reasons can be as simple as waiting to see their child graduate. Once the work is finished, the deceased usually moves on in peace.
5. Self-Appointed Guardian Angels - These are loved ones who stick around after death to watch over someone. It can be a deceased husband watching over his elderly wife during the last of her days. It can be a young mother who died before her time watching over her children as they grow up.
6. Wasting Time Between Lives - As in reincarnation. They're waiting for the next life to come around. What better way to waste some time than being a ghost. Coming and going from the planes as you please, enjoying yourself during your sightseeing, visiting old friends to see how they're doing, and the list goes on. They're not here and not there - there just waiting in between.
7. Messengers - These are usually in the form of a loved one. It can be a warning of certain danger or future events. It can also be a spirit coming to ease the pain from a grieving loved one. My mother and my grandmother have both had the latter happen. With messengers, the spirit is not always deceased.
8. Still Living - These people can be dreaming or having an out-of-body experience (obe). In the case of dreams, the person doesn't usually know they're walking around in the form of a ghost. With intentional obe's, the projector knows what's going on but their intentions are generally harmless. I've personally seen my uncle come walking out of his bedroom, look at me and then turn around and walk back into his room even though at the time he was sound asleep in a hospital bed 5 minutes away. He died about a year later.
As you can see, these 8 types of ghosts all have 1 thing in common - they're all human. Classifying them as orbs or echoes is, in my eyes, disrespectful. Sure they take on a number of shapes and appear at different times and places, but they're still human nonetheless. They still have feelings and should be treated with respect. If you suspect you have a ghost in your house, talk to it. Invite him/her to come watch the T.V. with you and the family. It's going to happen anyway but if you ask them and start treating them as more than a Hollywood nightmare they'll start showing respect in return. Yeah, this sounds a little corny but I've been doing this for years now and it works.