A live-aboard can never cruise and a cruiser is a liveaboard while cruising.
You can cruise on a motorcycle on a car, on an airplane or a in a boat. Cruising is an act meaning to be in motion with no other objective than enjoying life and discover new places and new peoples.
Cruising is different from voyaging, on a voyage you have an objective, arriving somewhere and in fact if that is made as fast as possible, a voyage can exclude cruising, for instance a non stop circumnavigation or an Atlantic crossing.
Cruisers don't travel in packs or go on organized touristic voyages (that's a touristic tour), they have an open schedule and do what pleases them according with their mood and with the positive interaction with people and places.
Cruisers are those that love cruising and that do that as much as they can.
Cruising is a way of life, even if life will not allow us to cruise all the time.
Obviously you can own a sailboat and not be a cruiser, you can live in one and not be a cruiser, you can even not own a sailboat and be a cruiser.
That's funny, I tried to see if my take was a personal one and look at the on line dictionaries and found out that we are doing some research work here:
The simply say that cruiser is a person that cruises
Regarding to cruise there are more useful meanings:
To sail or travel about, as for pleasure or reconnaissance.
To go or move along, especially in an unhurried or unconcerned fashion...
cruise - definition of cruise by the Free Online Dictionary, Thesaurus and Encyclopedia.
to travel without destination or purpose
Cruise - Definition and More from the Free Merriam-Webster Dictionary
to sail about on a pleasure trip.
to travel about without a particular purpose or destination.
Cruise | Define Cruise at Dictionary.com
sail about in an area without a precise destination, especially for pleasure
Definition of cruise in Oxford Dictionaries (British & World English)