As a trainer that does both one on one and small group training, there are major differences with cost being the big one. All of my group training people train together and work together, so there is that camaraderie that they receive by working together, training together and getting together outside of work that binds their friendship together. With that said, group training is all about a bunch of people having fun and working out together so it is more of a social thing for people. The person that can afford your one on one rates, wants more of a personal experience that revolves around them and their goals only. with one on one training, you can be more focused on your client and not have to deal with multiple people at any given time and whether you will get enough people for your group to make it monetarily worth your time. With group training, you can make your training like team sports training with the exception that it is not done in a weight room but on the field of play instead. Also, with group training, if you have the right number of people, you can triple your money for the same amount of time versus one on one training. I,personally, like training both one on one and small group training because it challenges me in different ways as far as workouts and mentally.