They're different to me. I personally like to participate in one-on-one tickles more, because it's easier to learn spots and techniques that work best by observing reactions without having to wonder if it's just that another 'ler is doing something at the same time somewhere else to elicit the reaction. That way, I become a better 'ler for that person, and we both derive greater benefits.
But for observing, I'm more often fond of multiple 'lers because of the intensity factor. I like to see women completely overwhelmed. Granted, I can usually do this on my own, but sometimes you better appreciate the very basic, primal overpowering and overstimulating by sheer numbers.